I've climbed short pitches of WI3 ice, class 4-5 rock, snow couloirs, and snowshoe'd in these boots. While they have some insulation, I would not call them winter boots. They seem fine for spring and fall mountaineering though. The construction seems to be a mix of leather and synthetic - no break-in time required.
The soles stick great on rock, even when wet, and have sufficient rocker to make hiking tolerable.
Fit: my feet measure size 9.5 US, usually I wear size 10 boots. My toes are wide and heels narrow. These seemed to fit great in size 10, but I have to use a heel lock knot to prevent heel slippage.
Crampon compatibility: seems to work decently with Black Diamond sabretooths (best to use new heel lever); Petzl Vasak leverlock. The soles are plenty stiff, though the front welts seem a bit small - this could be a concern with certain front crampon bails.
Warmth: my feet tend towards the cold side. I just throw in chemical toe warmers if there's any doubt. On overnight trips where it was substantially below freezing I've put them in a plastic bag inside my sleeping bag to keep them from freezing solid overnight.
Durability (update Jan 2007): They've lasted me two seasons so far. I've also led some alpine ice in them as well (hard cold blue stuff, not whitish neve).
I have been very pleased with them. I have used them on snow and mixed rock/snow numerous times (no vertical ice sorry). They work great on both surfaces and I have used both my Petzl Vasak (standard strap-on binding) and my G-14 with toe bail and both have worked great. I added some superfeet since the original insole wasn't very supportive. The boots are comfortable on long dry approaches and stay relatively warm and dry. Like any leather boot it, the better you take care of it, the drier it will keep you. Like someone else mentioned, there is zero break-in time. I knocked out 8 miles and 4000 feet elevation gain on the first day and they felt great. I definitely recommend them for hikes/climbs in the Sierras.
Best rigid shank mountaineering boot for the dollar. It was exremely comfortable on my first climb. Use it on mixed climbs with semi-auto crampons. I won't trust the toe-lug on steep ice. Just returned from a cold climb on Mt. Rainier where the insulation worked just fine. I added extra waterproofing and didn't get wet on soft snow down low. Very happy so far.
I got these boots a few seasons ago, and used them on everything from late-winter/early spring mixed routes (rock/snow) in the sierra, springtime sprints up Shasta, to chilly moderate-altitude climbs down south (Orizaba, Illiniza Norte, Cotopaxi...).
I used to like specialized gear, meant for the occasion, etc. but these are really wonderful all-round(ish) boots. They climb rock well, they hike well (i don't lace em all the way up on long approaches), snowshoe well, i've only climbed ice in them up to 65 degrees or so, but they were rad there as well. They really excel on mixed terrain, steep snow, etc.!
they are insulated, but not warm like a double plastic. i usually run pretty hot, but my feet start to get cold after a few hours out around zero degrees F. The waterproofing is good, but not great. I've never had them soak through all the way, but flex spots will start to get damp. I'll probably beef up the waterproofing soon.
they're nice and compatible with my grivel g12s (semi-auto), and that's the only crampon i use anymore.
Most importantly to me though, these are the most comfortable boots i've owned.
They are the most comfortable boots I've ever owned including hiking boots. They are relatively lightweight and surprisingly durable for the weight. They've never leaked and don't feel bulky or cumbersome which is nice for climbing. My feet have gotten a little cold when stuck standing in snow/ice in the shade for a long belay in cold temperatures but nothing serious. My plastics haven't been off the shelf since I got these. I wore my hiking boots out a year ago and haven't bothered replacing them because between these boots and my approach shoes, I don't seem to have any need for them any more. I've used them with my Stubai lightweight aluminum strap on crampons and my Petzl Charlet Vasak Leverlock Crampons and they've performed beautifully. I've used these boots on a very wide range of terrain and have no complaints. Even with a very heavy pack, my feet have been happy. I have wide feet and a bunion on my left foot so boot fitting is a bit of a nightmare for me. I had the pressure point on my bunion stretched out by these guys: http://www.quickcobbler.com/ and they now fit like a dream. I did end up with a full size down from my usual size which was surprising. All my other footware is 7.5 to 8 but I have a 6.5 in these boots.
Picked these up for heavy backpacking and mountaineering and haven't been disappointed at all. They just fit. As all feet are different and not all boots are created equal, I tried many other makes and models. For the price, these can't be beat! Took them up Mt. Daniel in Feb, Rainier in Summer, other various places in mixed spring/Summer/Fall conditions in WA state. Cold toes a few times, but mostly during stationary work (belays or resting in snow). Used with Grivel G12's (full strap) and BD Makos (Step ins- near vert ice) and haven't missed a beat. I think they are a little flexible for my Makos, but I didn't have pop off issues... They have great camber and hike well. Only downside is I steped on the leather with my crampons on... leather has a hole filled with silicone goop, but I missed the GORE so, still no leaks. I beefed up the waterproofing with a good baked in SNO SEAL application. Helped alleivate water absorption on long slogs. I'm 6'5" 230lbs. With 60lbs of gear, I still have happy feet.