"Normally, I wouldn't post anything on this forum until it had been used enough to evaluate, and then only if it worked well."
Famous last words. After replacing the hipbelt tightening system with the pulley type used by Osprey, loaded up the Bean's AT55 with about 15 lbs, 18 lbs including the pack, well distributed, and discovered that pack has a tendency to slip down, right behind the small of the back. With the Osprey system, the belt can be severely tightened, so did so, and found that to stabilize the pack, the belt has to be tightened so much it gives whole new meaning to the word, "squeeze."
So, back to the MYOG pack also mentioned in the earlier post that uses one of the old Osprey heat moldable hipbelts. The belt is a little on the heavy side, but it locks the pack onto my back with no slippage. A few small repairs and the pack is ready to go again.
May try sewing a high friction lumbar pad onto the AT55 to see if that eliminates the slipping, but later for that.
Wasn't sure whether to post this here or on MYOG, but the earlier post was on this thread, so this one is also.