Okay, I posted a WTB in the gear swap forum and it turned into a very helpful reference to a number of UL packs. I wanted something small than my GoLite Jam, under 50, and capable of doing an uber-uber UL overnighter. Of course something like a G6 would work, but not for $50 unless I found one used.
Someone mentioned the Patagonia Travel Pakc and I work acorss the street from Outdoor and More in Seattle. It's a nice little Mom-Pop hiking supply and I knew they had the Patagonia packs in stock.
I'd rather have the REI Zip pack I think– about half the price and the same weight and roughly the same features.
Of course I had a look at some othe packs and I found the Outdoor Research DryComp Summit pack on sale for $50 (see http://www.outdoorresearch.com/home/style/36600). It solves a lot of problems– variable capacity, roll-top waterproof closeure, 12.2oz/346 weight, and dead simple. I could cut the compression/waist straps and bring down the weight a little.
I could overnight with this one in my sleep– outside pockets would take a couple water bottles and the daisy chains would allow straping my sleeping pad on the outside– if I can't make it work inside as a frame/support. The capacity is 1800ci/30.9 liters, which I think is respectable for a 12oz waterproof pack. The fabric is pretty tough stuff too– I wouldn't be afraid to bushwack with it at all.
So, thanks for your help and put this pack on your watch list. I'll report back after a couple good walks with it.

