Also used the Lowa's on a summit of Mt. Rainier. Have had these boots for 2 years. Took a little breaking in, but any mountaineering boot will. Probably the perfect boot for the climb if you dont want to use plastics. My feet were warm the entire climb, thus proving everyone is different, and not to rely on these reviews totally. Waterproof, but they will seem a bit soggy on the inside from sweat. The outside leather will absorb some water, which becomes a problem the next morning when they are frozen. They will flex just a tad, so its possible to wear on the approach hike to the base camp. Very comfortable for average width feet. The solution to the 3/5 review is; break in first, switch to camp booties when you reach base, and dont think that the "warmest" sock is necessarily a good thing. They might be too thick and only cause the negative effect after securely lacing up your boots by hindering proper circulation. Recommended (in my opinion) for most U.S. summits.

I tried 2 types of Scarpa (charmoz and summits), 2 types Asolos (expert gv and makalu), 3 types sportivas (trangos, glaciers and nepal evo) and a pair of Kaylands (can't recall which). While both Scarpa's and the expert gv's and the Nepal Evos fit GREAT! The minute I put these on... it was love. Thick or thinner sock, stock insole or the green ones. AWESOME! I usually suffer in the toe box and across the width. Not here! great rocker for approaches, a little more flex than other stiffer boots makes for easier approaching. Haven't had any issues since purchase with my feet. I am a tough customer with shoes/boots. Feet must be comfy or they detract totally from any climb. After too long in crappy fitting boots-these have been bomber. Did I mention they are lighter than the summits and Nepal Evos too! At least they feel that way becasue they fit so well.

Here's how it breaks down: I fit a med.-higher volume, slightly wider 11.5US size (45-45.5 eu size) boot/shoe.

Scarpa:
Summits-had front to back sliding issues. Otherwise loved them in a 45.5, 45's fit until I did a toe tick-then pain resulting from toes jammin into the stiff toe box. Thicker sock recommended as well as green insoles to help with the sliding. Also had a bit of trouble sinching them up since they were quite stiff leather. great boot. Almost bought these.

charmoz's I had concerns with durability, but were great at 45.5 size too, 45 was narrow. Good flex for quick assaults, likely not too warm for cold weather hauls.

Sportivas (trangos and glaciers)-toe box TOO SMALL! and pinched in the width. didn't even have to lace them to know they didn't fit. Kaylands fit like these on my feet. too narrow.

Sportiva Nepal evos--rocked! Just too much boot for what I will be doing most of the time in the WA Cascades, and a bit more than my pocket could swallow. Were also a bit stiff considering long approaches and may be warm in moderate weather = clammy feet...would love these for more technical stuff, possibly even use on some major domestic and international routes. Would be more than bomber on any Washington state mountain and likely so for Mt Hood and so on.

Asolo's-
The experts were great with a medium weight hiking sock, threw in the green insoles still ok, add a thicker sock = width problems, but toe box was still good. didn't matter which boot. They aren't insulated so expect colder feet on cooler climbs.

Makalu's just didn't feel right after the Lowa's.

Lowas- bought size 11.5. Angels sung when they hit my feet. Hasn't mattered since. Put some miles on them and plan to use them on many more. Ice, glaciers, trails. They just work for my feet.

Trangos + Charmoz + Lowa Mt Experts all have the same sole. While I haven't had major sole wear yet, I hear they wear faster than other sole types. But, they can be re-soled. I doubt the boot will wear out before the sole. Good construction. Have a buddy with the Trangos-his are busting up before the treads have...

These fit both my G-12's (strap style) and my BD Mako's (step ins) and perform well in both. But, for vert I think something with a bit more heft and stiffness would be better, but still good performers. A bit flexy for toe holding w/o crampons on rock but not bad.

I found them to have a bit more flex for the approaches than the Nepal evos, asolos, and Summits (right out of the box). I would put them a might stiffer flex than the trangos or charmoz, but more flexy than the summits and evos . The summits and Evos would likely break in, but see above for reasons for why I didn't keep them.

Take home message: Fit was everything for my purposes.

Wore these out of the box on a hike up to Rainier base camp (Muir) with liners and smart wool mountaineering socks. Destroyed my heels, out for a week with big ripped off pieces of skin. I blame myself, however, for not gradually breaking them in and not lacing correctly.Just summitted Rainier on Fri night, at Ingraham flats when sitting in the snow while tent went up I noticed my toes were mildly cold (wearing liner and the warmest smart wool sock). No biggie. After getting to about 12.5-13k ft. both me and my friend (same boots) noticed cold toes even while moving (albeit slowly as we got further up). Not overly concerned, but slightly uncomfortable, had to keep moving toes within the boot. This morning I noticed my toes are slightly numb/tingly, I believe I incurred some very minor frostbite. Weather at Rainier was described by many as "perfect", no clouds, warm, no precipitation whatsoever. If these boots can't keep me warm on Rainier with outstanding weather, it will probably just get worse from here. Sucks too because these run big (meaning long, they are narrower), no other boot has come close to fitting me yet (all too small or don't come in larger sizes, I wear a 13 street, 13 in these worked for me). For example, I tried one of the comparable leather la sportiva'a in a 48, toes hit the end and I guess a 48 is supposed to be a US 14. Side rant: Boot manufacterers please unite globally with consistent length sizing to the MM! Don't make us consumers waste time figuring out if you've decided to make your boot "run big" or "run small". The foot is 3 dimensional sure, but at least get the length right. Final notes: I'm generally more sensitive to cold, if you're not you may not have this problem, but I don't think my friend is super-sensitive to cold and his toes were cold, so who knows. These boots were light and comfortable (comfortable as far as full shank crampon compatible boots go), so if you don't think you'll have the cold problem and/or climb using crampons in something more mild than a nice day summitting rainier (maybe 20 degree clear weather with fairly strong winds) they might be a home run.

These boots are freakin amazing. They are definitely stiff mountaineering boots (like you would want), but they are comfy and have excellent freedom of movement at the same time. Straight from the box I have never had even the tiniest hot spot anywhere on my feet. I have even worn them with just liner socks and my feet were comfy as a clam. On rocky approaches these are great for ankle support and solid gripping soles. A crampon fitting side note: the BD Sabretooth pros fit on these very well, but the front bail is a little off. It does not fit flush with the boot and allows for side to side toe movement in the crampons (not good). I find the Sabretooth Clip crampons to be a perfect match for these boots. Very solid fit and no extraneous foot movement at all.