Rangerdogg,
I've used mine in Revelstoke, BC (high altitude) and it was cool at night -- got down to around 5 to 10 degrees -- and we still had the vents open for comfort. With the appropriate bag, I see absolutely no reason why this tent can't be used in the snow.
Others,
I've put about 20 nights into my Tepui which isn't a lot, over about 10,000 KMS - I just got it at the beginning of June.
It's a great tent with no complaints. I suggest taking some time to study how it goes together. For instance, the tent is secured to the platform via a fabric wrapped plastic dowel type thing that then slides into the aluminum channel on the base of the tent, as does the cover. I found that after setting up and tearing down many times, the tent would occasionally slide out near the edges. It's super easy to fix by sliding it back in -- in fact I don't consider it a 'fix' as much as I do an 'adjustment' that needs to be made when you set it up from time to time.
Additionally, I can't say enough good things about Evan and the customer service piece. I e-mailed him at 3 AM after my ladder had a bit of an issue; I explained I'd be driving through Santa Cruz the following day, and was wondering if a ladder swap would be possible. Despite he himself not being available he made super easy arrangements to have my ladder replaced and assured me that if for any reason it didn't work out, he'd mail it to me.
One thing I DO recommend though is spending the money on a 13 mm gear wrench. Most of the rigs I've seen posted thus far have a lot of clearance between the mounts and, say, the roof, but my JK does not. The rack is designed to be tight fitting to the roof and because of that it took time to keep resetting the wrench and I could not get a socket on it. On the first nut, I though "gee, a gear wrench would be handy". An hour later on the 8th nut, I said "NEVER AGAIN WITHOUT A GEAR WRENCH"!
So if you have $20 bucks, buy the gear wrench and keep it in your kit. Other then that it's super easy to attach. It can basically be mounted to any rail that is up to about 2 inches wide, and no more then about 2.5 inches deep. It is doable with one person but I found a second person made it a lot easier, especially if you have to get it high up.
If you don't go with the awning right away, its also very easy to rig up a tarp in lieu of that that provides some privacy and has a multitude of uses around camp.
Regards
Craig