I have the Kifaru Highcamp with the Bikini frame. I absolutely love it. Their Duplex frame is just as comfortable (to me) and probably carries 100lb+ loads a little better. Stone Glacier also makes some pretty excellent packs and I wouldn't hesitate to get one of their packs either.
The bottom line is, there are currently several really good lightweight packs that can haul pretty big loads in relative comfort. Once you narrow it down to several manufacturers, I think the most important factor at that point is how well the pack fits you. You wouldn't want to go hiking or backpacking in a pair of boots that didn't fit well and were uncomfortable, and I believe the same holds true for packs. Don't buy a pack that doesn't really fit you very well just because it has an elite name.
Chris
