Does weekend photo trips count ?
Average load about 12kg. (2x 1L water bottles + rest of camera gear) on a LowePro PhotoTrekker. Very comfortable and good for long distance trekking as what LowePro wants it to be.
Depends on the length of the trip. Short weekend trip, I use my Crumpler Budgie Smuggler in addition to a big army type duffel bag or my haversack. The Budgie Smuggler can fit my 3 prime lens kit together with a camera body attached and a speedlight, filters and 4-5 rolls of film.
Longer trip, then I take my Crumpler Farmer's Double together with the duffel bag or haversack. Same kit but more film and a backup camera body. The Farmer's Double doubles as a day bag, can fit water, jackets, food etc.