>I hoping that it will be the Bibler Tripod Bivy if light snow loading is expected (i don't yet own this bivy, so any comments for the cognescenti would be apperciated).
I'm an owner of the Bibler Tripod, and it really is a bomber bivy. Once you seal up the seams, I'm pretty sure you could ride out a hurricane in that thing and still be warm and dry. I got mine NIB from a friend for $50, and have been quite happy with it, minus the 2+ pounds weight. However, I'm not sure that I'd spend $300 on one.
Anyways, to answer your question, I haven't yet used my Tripod in the snow, but the three pole design should shed snowloading pretty well. Plus, you can always "flap" the bivy a little from inside to knock snow off the top if it's really coming down. I'll be using it tomorrow night for a 10,000ft bivouac in about 4 feet of snow sans tarp or other cover, but there isn't any snowfall in the forecast, so I'm not sure I'll have a better answer about snowloading for you after, but I'll report back and tell you how it does otherwise.