Remember the tale of the princess that could feel a pea under her mattress? In the same vein... how much weight can you add to your pack weight and tell a difference?? I mean a point where it begins to bother you. Also any thoughts as to the "sweet spot" of pack weight to comfort (less fiddle fart time, temperature range cushion,ect)and list choices that seam to make this comfort most noticeable.
I feel stuck at 8.5 -10 lb base. Every time I attempt to go lighter I experience a freak temperature drop (in Aug), wind driven rain, need the repair kit (blown shoe, pack strap).

I don't know about your question, but I'm around a 10 lb base weight as well, + or - a pound or two depending on the trip. I've though about trying to go lighter, but at this point, it becomes exponentially harder to drop weight and still keep my comfort level.

I personally don't feel stuck. I'm very comfortable, and very light. That's my sweet spot.

My thoughts are that a.) depends on what pack you are carrying, b.) if losing an extra pound means sacrificing safety then carry the extra pound and c.) if an extra pound finds you suddently carrying a crippling load then get to the gym. Quickly.

I have a set of weights and kept adding a few lbs at a time to my pack until it felt uncomfortable for me. You could maybe try that out until you find the sweet spot.

I have also done the same thing to simulate food weight as well.

Base weight is fine for comparison with others across the board... but total pack weight is what matters on the trail.

As David pointed out, the pack you carry matters as well.

My sweet spot -- the point where I can hike all day, everyday, and hardly feel the weight on my shoulders:

o low to mid 20's with a frameless pack
o mid to high 20's with a lightweight internal frame