Adam L.wrote a review of La Sportiva Baruntse Mountaineering Boot - Men's on March 26, 2014
Familiarity: I've put it through the wringer
Fit: True to size
I think these boots are pretty fantastic. I use them for winter mountaineering and ice climbing in the northeast (mostly in the White Mountains in New Hampshire). I have yet to have cold feet in them, and I've been out when the temperatures were well below 0 F. I really like the flexible ankle, which makes the boots quite walkable, and is also really nice for more technical ice pitches. The lacing system is old school, but works really well and allows you to dial in a perfect fit. These seem to work well with almost all step in crampons as well. I haven't had any issues with durability and expect them to last quite a while, though I do think they will be slightly less durable than Nepals or another full leather boot.
I wear a size 11.5 in street shoes and running shoes, and I found that a size 45 fits me best. I am not an easy fit for boots since I have a relatively wide fore-foot, but a narrow heel (I also have bone spurs on my heels). I get good heel hold from the boot though. I tried a 46 also, but this seemed too big and I got a bunch of heel lift when trying them out on the stairs of my apartment.
One comment I will make though is that since these boots are hand made (or seem to be) there can be quite a lot of variation between boots. When I got my first pair, I noticed that the rocker was quite different from one boot to the other, and that the height and stiffness of the ankle was also quite different between the left and right boots. Even the sizing of the boots seemed different between right and left (and my feet are the same size). This was actually very obvious when walking around my apartment, and the fact that my stride felt very different from right to left was pretty annoying. I worked with Backcountry to resolve this and they were fantastic about helping me, but I thought I would throw this out there as one issue I had with the boots.