"I have considered the torso-lite... but I'm a front sleeper... so I find I need a pad under my knees. The torso-lite is pretty tiny"
I'm also a front (stomach) sleeper, plus I don't sleep well on foam pads. I had a prolite 3 too and it's pretty confortable but I'm now using a combination that to me is more comfortable than the prolite 3 short plus more verstatile, at the same weight. I use this combo with a Gossamer Gear G5 pack.
I use a combination of the BMW Torsolite and a Gossamer Gear Nightlight Torso pad. The total weight is 13.25 oz with a total legth of 61 inches (32 inch Torsolite + 29 inch Thinlight). That makes it 13 inches longer than the prolite 3 and the torsolite is actually more comfortable and a little warmer than the prolite 3. The thinlight is almost the same thickness as the torsolite so you can't really feel that ridge or "dropoff" from the edge of the pad.
This system has several advantages over the prolite 3 at the same weight:
1. Longer length (61 inches vs 48)
2. Thinglight torso pad works better as frame pad in a Gossamer Gear pack than the inflatable pad.
3. Don't need to carry repair kit for torsolite since you can always reverse pads (thinlight under torso with torsolite under legs)
4. System is a little bit warmer and more comfortable.