I'd say 20 lbs is pretty reasonable if you've tested it, and you can carry it a good distance.

My tent and sleeping bag alone account for 21 lbs 3 oz of my BOB. I'm guessing the entire BOB is about 50 lbs easy. I can carry it with confidence even after recovering from a back injury. However, I'll tell you that strapping in can sometimes be a trial if I don't get the swing-up correct and the shoulder straps get twisted or there's nothing to rest it on while I squat thrust the sucker. LOL

The tent and sleeping bag load could be lightened pretty easily if I scaled back a bit. What I have now is cold weather gear and truthfully is overkill in this climate unless I was high in the Appalachians in the dead of winter.