I have used these on 3 winter ascents of Mt. Washington as well as ice climbing in Stowe, VT. I had very little time to break them in and found them to be very comfortable. They kept my feet warm in very cold conditions. They take my Lynx crampons perfectly. I cant wait to use them in the Tetons in a couple of months. I only have a pair of Mammut GTX boots to compare them to, but these are much more comfortable. Street shoe size 10.5. After trying on several pairs I kept size 45. I have had no issues with heel slippage, hot spots, or toe smashing. I wear a thin Smartwool liner sock, or a midweight Darn Tough sock only.

Initially purchased a few years ago for Orizaba, and since used (in no particular order) on Orizaba, Adams, numerous Colorado 14ers, Rainier, Orizaba again, Whitney, Ouray, etc etc. I added Dr Scholls sport insoles.
These things are awesome. They are insanely comfortable. The only time they've hurt was on a 17 mile day on Snowmass, and just about anything would have hurt at that point (they didn't even rub, just sore soles from a heavy pack). Laced for it they hike nearly as well as approach shoes. Cross and crank the laces, though, and they turn into front pointing machines that'll let you run laps at Ouray all weekend long. The best technical ice boots I've used.
Paired with polartec socks they're comfortable down into the teens for ice, single digits for alpine.
Summary: If you're really into ice, these are about as good as it gets. If you're more into mountaineering, there is no boot in your gear closet better in this temp range. If you're into both, it's your lucky day.

i used these shoes on mount Kazbek and they were great. Im going to try them in Island peak in few months. I read on serveral websites that they will perform good up there.

I used a pair of these as rentals from RMI adventures; climbing Mt. Rainier. I ended up with blisters starting in the heel. Looked, read and consulted with other climbers along with testing other boots after my climb, only to come back to this boot. I learned to appreciate the boots lacing system and realized I should have used an insole to get the volume right. I chose the Superfeet Blue Insole. I'm going to do a significant volume of training/hiking in these boots and work on sock choices under various cold conditions.
I didn't realize how strenuous climbing would be and my metabolism burns about 10-15% above average. My feet stayed plenty warm in these boots even in below 0 degrees F with 15-20 MPH winds with alpine night time ascents. I use single sock layer but again, do what you need to get the fit right.

True to size, super fit, not a blister to be had. Minimal to zero break-in. Size up .5 to 1.0 for best fit with socks. Feet stayed warm and dry on Mount Rainier, all the way up and down. One of the best mountaineering boots I've worn.

I used these for ice climbing in Peru last weekend. We had a 4 mile approach, steep scrambles, and glacier traveling. they were excellent for hiking because they were light and had strong ankle support. Scrambling was easy because the souls were stiff enough to toe a rock but flexible enough to actually feel it. They were extremely warm and comfortable on the glacier and I had no issues with popping crampons. They were stiff enough to stand on your toes with cramps on without the feeling of slipping or calve fatigue. Kicks felt like butter!! I bought these at the discount and I'm super glad I didn't go cheap. I'm using these for Alpamayo and Aconcagua next year so I'll let you know how they go.

Sizing: I normally wear 42 but I went with 43 to accommodate thick socks and they fit perfectly. Tight enough for support, feeling on mixed climbs, and it wont rub me raw. Loose enough to wiggle your toes.

Had the chance to try these out on your normal everyday ice climbing route, and a chance to kick my way up Ta Chute in Little Cottonwood UT, in search of some ice routes and they performed great. My feet stayed warm and dry, with a 3000 ft ascent kicking each foot and they did really well tramping through the woods at 5am in search of the valley we were trying to find.
The sole is very stiff and reduces foot fatigue when you're on vertical or nearly vertical slopes, tread is great, and the crampon grooves fit nicely with my Black Diamond Cyborg Clip Crampons.
All in All, I'm excited to test these boots out on some serious peaks above 14k!!!

I just got these boots for times other than double boot territory and they are terrific. Due to very cold feet, I've used the Spantik boot for years above 14k with good results, however, I needed a more nimble boot. These were surprisingly warm in about a foot of snow on Mt of The Holy Cross above 14k. I used only a pair of compression socks and was very warm. The fit is unbelievable. For a size 8.5 I ordered a 41.5. The heal lock is perfect and there is a ton of room in the forefoot. When I first looked at the boot it seemed as if the forefoot would be too loose, but in fact the fit is better than any other. I took it on 12 miles and 5k elevation gain right out of the box with no blisters. Way more comfortable than I could have imagined. Highly recommended for anyone looking for a cold mountaineering boot.

I got these boots about a year and a half ago and have used them in the Tetons, Lost River range, Lemhis, and Hyalite. They are well made and keep my feet warm all the time. There are locking D rings so that you can adjust how tight the lower and upper parts of your feet are. This makes the approach hike much more pleasant. When you do tighten up your heel for the climb it stays in place perfectly. I love these boots and would definitely recommend them.

Just had these boots on the top of Rainier, weather was cold enough that I needed all 5 layers and my feet stayed warm. Inside of boots have a smooth feeling all the way around and heel lock is great. Wore these with minimal break in no problems. You can definitely tell these boots are made with the latest techniques. Probably saw more of these on Rainier than anything else, maybe due to the fact that Whittaker Mountaineering rents them. I would recommend sizing up maybe 1/2 size for a comfortable fit and fine tuning it with socks, this is what worked for me, different thickness of socks makes all the difference on dialing in a fit. Boot works well with BD automatic crampons but front toe welt is small than some other boots. Hybrid crampons would definitely work well with these boots.

On ice, heel lift is the enemy of all things fun and good. If your feet aren't good, everything else falls apart. These boots (for my feet, anyway) are simply perfect, locking everything down and creating a stable, super rigid platform. They're amazingly light yet completely protective.

So that's awesome, but what if you don't climb ice?

Loosen the three pairs of speed laces at the top of the ankle and these will hike really, really well. I don't mean suck-it-up approach style... I mean these hike better than 90% of hiking boots. As long as your ankle isn't locked in, they flex comfortably to move over variable, rocky trails without any issue.

I haven't thrashed them for a season or two yet so I can't comment on the durability, but everything else about them is absolutely awesome. And LS has a solid reputation among guides who have used various incarnations of the Nepals for many, many seasons, so I'm unconcerned. The fit and finish, and craftsmanship is evident throughout. These are exceptional boots.

Quick word on fit - I was climbing in Scarpa Jorasses Pro size 44 and went up to 44.5 in these, but I have a wide forefoot. Sneaker size is 10.5.

Third time writing this because apparently I'm too stupid for the internet.

I bought these after suffering through double plastics for too long and the difference is palpable. On ice they feel super stable while staying light and agile, immediately I saw a difference in the confidence of my feet and my overall comfort on the ice. I've also used these for winter "mountaineering" in the Northeast, they've been a huge relief, despite the rigid sole they walk/hike brilliantly both with and without crampons/microspikes. Construction has been bomber so far, I've only used them for give or take half a season but there is nothing so far telling me that the construction is inferior to the Nepal Evos. A sticking point for many people may be the price, I got these at a discount so it wasn't an issue for me, but the real difference between these and the Evos is 4oz and 70 dollars so take that as you will. These are very nice boots and I can't wait to use them for years to come.

Size right! Either go to a brick and mortar store to try on various sizes or order a few pairs here and return the sizes that don't fit, Backcountry is really good about that.

Street shoe: 8-9
Nepal Cubes: 42.5