I plan to buy a pack from ULA
ULA-Equipment. The reviews for the ULA packs are typically outstanding.
I am currently leading toward the slightly heavier and larger Catalyst at 2 pounds, 11 ounces. It seems better suited for lashing on snowshoes for winter hikes and carrying heavier loads, which I occasionally require. The Circuit also seems to be a great pack at 2 pounds even. Still haven't made a final decision yet...
I also agree on the Granite Gear packs. Have met so many people who like the Vapor Trail and Ozone Nimbus. Don't think you can go wrong with either one of those packs.
Gregory also makes the lightweight G-Pack and Z-Pack that have a very good reputation.
Personally, I think it is worthwhile to look for weight savings in backpacks. I'd rather carry less weight than have more features you might find in the heavier packs. I can live without them. I also think that lightweight packs can be pretty durable, too.
If you decide to go with a smaller sized pack, you might run into space problems with a synthetic sleeping bag. If so, you might need to switch to a down one, which compresses very small (and typically weighs less).
Good luck with your decision!
Marty