The Baruntse is my bomber high altitude boot. I took them on Aconcagua and wasn't cold once, and if I do Denali not on skis (I'll probably do it on skis tho...) this is the boot I would take. La Sportiva tends to be a brand that does not fit my feet well, but the wide exception to this rule is the Baruntse here, and my Mythos. The Baruntse has stability, and is fully crampon compatible if you've got those. I got my inner lining boots heat moulded at Feathered Friends, and that gave an even snugger fit.
I bought a size that was a bit bigger for my foot, and I almost feel like they're slightly too big, even at altitude, but oh well. For what I've used them for so far, they've worked well.
Pros:
Quite warm
Stiff and very controlled
Mouldable lining boot
Wide
Cons:
Heavy, but that's a given with a double boot