The Summits are definitely warmer. I'm actually wearing them right now and my feet are toasty.

The Summits are a much more "hardcore" mountaineering boot than the Charmoz too. If you're looking to tackle vertical ice, I would highly recommend the Summits over the Charmoz.

Yes!

Yes they do. I'm wearing them right now and can see the little tab you'd pull out to fit the GSB spike in.

Scarpas are generally on a wider last. I have duck feet (wide at the toes) and these fit well. Sizes do seem to run a little smaller so you might have to upsize a bit...but everyone is different on how they like the fit. The heel does tend to be full so be careful of heel blisters (not a problem for me but has been for many others). Overall a great boot. I used most recently on a admittedly mild Shasta climb and they were awesome...no blister, no pain, warm, dry...couldn't want more than that.

La Sportiva!!!

La Sportiva trango boots are awesome, check those out

Like fish to water.

A 10 to a 10.5.I don't know how high you are going to climb . Pete , remember that you will also be at lower altitudes on the approach . I do not regard the summit as a high altitude boot . Scarpa has special boots for 6000 metre plus peaks . I wear one 1/2 US size bigger than my shoe size . My shoe size is 11 1/2 and I wear a 12 in scarpa boots , this allows for two pairs of warm socks . If you are going to climb at 20,000 feet in winter you need to look at Scarpa high Altitude boots that come with an attached gaiter for added warmth.

I am not sure what the temperature rating is, but the lining is not removable.Bonnie , if you want to wear these in the lower 48 states for winter you should be fine . You must make sure that you wear two pairs of warm socks .The summits will also be good for long approaches in the summer in the California Sierra . If your plans include Alaska , you should consider a plastic boot designed for colder weather . On a scale of 1 - 10 , 10 being the warmest boots available I would rate the Summits as a 7 . The Scarpa Inverno plastic boot is a better winter boot for technical ice and general cold weather here in California . How warm ones feet are is obviously very subjective . I hope this helps .Simon in Joshua Tree .

I would consider these average width. They're a bit wider than La Sportiva's but not really considered a wide boot.

Yes.I have used my summits at Lee Vining Canyon and found them to be good on the ice there . The ice there is anywhere from 60 to 89 degrees in angle .These boots do flex a bit as they are a general mountaineering boot . Plastic boots do not generally flex but are much heavier .

I have found these boots to run very true to size. In my opinion I'd shoot for a size 13, which is a 47 in these boots. Hope that helps.I am a US size 11 1/2 in shoe size . I like my Scarpa boots to be a 46 which is size 12 US , this lets me wear two pairs of socks . Eben , you must physically try on a pair of scarpa boots to learn your size .I once ordered three pairs of the same boot from Backcountry , I sent back the 2 wrong sizes and had a credit on my credit card way before any payment was due . I paid about $ 15 to ship them back , but it was much cheaper than driving to the nearest store ( 90 miles ) .