The Kestrel 48 is a nice weekend pack; I've used one for exactly that purpose for several years. (Note: as other posters said, the gear you use makes a difference. I use a Carbon Reflex 1 tent, NeoAir All-Season 66" pad, down quilt, and minimalist kitchen.)

My only quibbles were minor: I don't like two-compartment main bags, and I could never get more than about a 5-degree angle on the load lifters. When only carrying 19 pounds for a weekend, neither of those things is a big deal. I also had one big like: the long vertical zippered pockets that held my rain gear perfectly, coupled with the built in rain cover.

While I'd recommend the Kestrel 48 if you can use very light (if not quite ultralight) gear, and travel with minimal gear (no candle lanterns, bigger tents, complete cooksets, etc.), I'd also encourage you to take a look at the Osprey Atmos 50 (the trampoline-suspension equivalent of the Kestrel 48), and the Deuter ACT Lite and ACT Zero packs.

Over Labor Day weekend, my local outfitter (who claims to be my gearaholics sponsor, but I'm starting to get suspicious) managed to fine tune a Deuter ACT Zero 50+15 to fit me. I've always liked the design and build of the the Deuter packs, but hadn't been able to get the load lifters to get more than a zero angle on the load lifters. In the current year version, it appears that the point where the load lifters attach to the pack frame is a bit higher, because I now get about a 30-degree angle on them. (Or else I didn't know how to tweak the fit in last year's model.) I do like the the single compartment design (no zippers to break) and the fact that you can adjust the point where the load lifters meet the shoulder straps; I also like the hipbelt stabilizer straps (not found on the Kestrel.) I'm going to miss the long vertical outside pockets - but if the fit is better, it's a small price to pay.

The ACT Zero 50+15 also has another feature I like: the +15, which is a large extension collar. The Kestrel has a small extension; I could probably fit my winter clothing, or an extra 4 days' food in it, but not both. The Deuter has enough room for both - but when I'm not doing either, it rolls out of the way, and I'm not trying to figure out how to shrink a too-large main pack. (A 65 liter pack, with no extension collar, is hard to use with a 50 liter load.)

I'm not getting rid of my Kestrel 48 anytime soon - but I'm going to give the Deuter another try. (Daisy should chime in soon, probably to give me a hard time about finally seeing the light and going over to a Deuter pack. Or is it you, Mouse? ) The worst that can happen is I revert back to my Kestrel.