More info on the comparison of CS to down in an UQ, per Paul's IMO conservative ratings:
Flame thrower 40X54 UQ with 9 oz of 800 down, total wt 16 oz:
Jarbridge 42X58 ( a tad bigger than FT ) with 1 layer of 6 oz/sq.yd standard CS XP ( ? ) total wt 20 oz:This quilt is taking most users easily to 30 degrees and some even lower. So far we have heard of one user hitting 19 and they said they were toasty.
But several folks here have gone lower and I think 1 person said they were warm at 9F?3 Season Rated to the 30's for most users
So, basically the same rating from Paul, the JB is a tad bigger than the FT and weighs 4 oz more. Again, to me, that is not a huge dif.
So OP Nathan, I don't think - at least for UQs - that warmth to weight is a big enough reason to choose down, especially if giving any consideration to performance when damp. Or if sleeping out in a snow storm with no tarp! And of course there is a pretty good initial cost advantage to the Jarbridge.
Much smaller pack volume would be a good reason to choose the down for those with smaller packs. And maybe greater longevity.
Edit and PS: Cannibal, I have not been able to verify any difference elsewhere, but I guess Paul knows, and he offers that Apex upgrade that he says is 5-10 warmer than the normal XP in your quilt. If that proves to be the case, then the difference between down and CS shrinks even more.