Tim, your post alone is a great reason to use EE for your quilt needs. You not only let everyone know about a price increase well in advance, but you ask the people that are buying them what they want. I tried to answer a couple of your questions below, but am not that experienced, so may not be that helpful.
RevX - People buy this because they are looking for value, so I don't see why adding 1-3 ounces and keeping the price low would be that big of a deal. Looking at the market, I don't see much competition at these weights and prices, so I think you still have something with this one.
Rev - The new price point still seems like it is considerably below the market, but I have not compared weights that much. You may have already done it, but putting together a market study (products this line is competing with, price, weight, features, etc) could help you out in regards to understanding how this one will sell. One trick is understanding if your competitors will be increasing prices in the future as well or if they have some type of hedge against down prices (doubtful, but you never know).
New Quilt - I like the idea of you offering a super light weight downtek bag. I have read that 900 isn't that big of an improvement over 850, but not certain if this is legit. I like the versatility of a non-sewn footbox, so likely wouldn't want this. Could you get most of the weight savings by losing the zipper, snaps, and draw cord and go to a button style. You could fold the two lower corners under the quilt and button at the centerline. This would leave a point at the the end where you could button this under creating a footbox of sorts. It would reduce the length a bit, so may not work, but an idea.