"waterproof down" sleeping bags for big wall use?

I'm considering a downtek bag because its half the size and 2lbs lighter than my current synthetic. However, im not convinced it would actually do the job if i get caught in a rain. two thoughts i had would be to carry a SOL waterproof emergency bivy (only 3 extra oz in the pig) and maybe scotch guarding the shit out of the bag. Any experience or thoughts? Any "yer gunna dies"?

Hey Lars,

Are you talking just riding the storm out in your bag, uncovered? Bit of a complicated question, because the downtek isn't waterproof, really - just very water resistant. In addition, even if the shell is pertex or something, the seams are the weak link for water invasion in anything beyond a light drizzle.

The emerg bivy sack will last you one night, most likely. Those superlight dealios are not durable at all, shifting around on a ledge/rock does a number on them.

All that said, I'm not a fan of an uncovered synth bag in the full-on rain, either. Perhaps I'm not getting your question completely.

maybe this helps a little:

mountainproject.com/v/hydro…

I guess to clarify my question... Synthetic is obviously the best insulator when wet, and down tek is inferior but better than plain down. That being said, is synthetic SO much better than downtek thati should not consider downtek? If my partner and i both carried lighter bags we would shave off 4lbs of gear. I view that as room for an extra half gallon of water or other supplies we might need for safety.

I did see the other thread but felt like most of the discussion covered the wrong points.i.e. I don't care if yosar charges me for a rescue. I care to avoid the necessity for rescue in the first place. So do i accomplish that by moving fast with light gear and more water or by sticking to synthetic bags fir storm resistance?