FYI Kelty is offering 40% off their 3 externals (Trekker 65, Sanitas 34, Yukon 48) with free shipping. I snapped up a Trekker, been eyeing it a long time. It's not light, but my hope is that it'll be a worthwhile tradeoff for durability, weight capacity (esp. with large water carries), effectiveness of weight transfer, and ventilation. Also appears to have good space outside the packbag for attaching a CCF sleeping pad.

I previously tried a Tioga 5500. It wasn't too big (on me), and the frame is similar or the same as on the Trekker. The pack bag on the Tioga just extends outward a bit more, and takes up more of the vertical frame space too - so much so that a single Ridgerest pad pushes up into the packbag from below. It also had an issue with the torso adjustment ... the vertical strap used to tension the mesh back panel was not long enough for the case when the pack frame is set to the maximum torso length (22, mine). There was just not enough length in the strap to thread it back through the tensioner and secure it. Hopefully the Trekker won't have these issues.