The night before we hit the trail head I was up 3/4 of the night weighing and re-weighing everything in my pack to reduce it from it's 92 lbs. By the next morning I had it down to 86lbs but not w/o a lot of very hard choices.
My Backpacking gear was already as "UL" as the alpine tundra and 25 days of food weight,tent,cooking gear,sleeping bag would allow. Throw in the all the fly fishing gear to the mix, add in a heavy DSLR w/ 3 changes of batteries and a tripod is out of the question. CF cards weigh next to nothing. If I had "any" doubt about a particular shot that I really wanted, I'd review at full review screen magnification and reshoot if necessary until I got the results I needed.
The VR of the 70-300 worked perfectly at the long range and the F2.8 of the 17-55 made up for the lost 5mm at the wide end in allowing a lot of handheld shots that would have been much harder w/ the 12-24. In retrospect, the few places I "Really" missed the extra 5mm of wide range,.... I don't think it would have been enough.
Picture Yosemite Valley w/ 5,000' tall walls on either side of you but standing at the bottom of a 40' wide canyon. I'm not sure a 10mm would have been wide enough.
Also, out of the entire 25 day trip, 17 days were traveling cross country w/o any trail through miles of this (You HAVE to expand to see what I'm talking about)
