Formerly Known as Newbie
Join Date: Mar 2002
Location: Helsinki, Finland
+1 on panniers.
If, however, you insist on backpack, I was going to suggest a suitably sized Deuter. I see you went that way already. We have one of their middle range backpacks (maybe 40-50L of volume (1)) and the frame does a reasonably good job keeping the bag off your skin and providing space for ventilation. It seems the frame is not used in their smaller backpacks, at least not in the models we saw here.
(1) As a side note, has anyone else noticed the hiking bag capacity claims are ridiculously inflated? I was in search for a large hip pack and saw an Osprey Talon 8 in a web shop, advertised as 8 liters. Went out of my way to actually see one in a store, and a good thing I did. The bag was barely the size of three 1,5L PET bottles in total (happened to have one with me). I showed it to the doubtful store clerk and asked why they had BS descriptions in their web shop. He admitted the capacity was way short of 8L, but "that's the manufacturer's specs, so we're good". Ummm... legally speaking no, you're not.