I've been shopping for a pack for my seven year-old son, and I think I've decided on the REI Comet. It has adjustable straps to change the torso length; at its smallest setting it fits him perfectly, so I think it's a pack he'll be able to use for at least the next four or five years. Any opinions on this pack? It's a bit heavy at two and a half pounds, but the Osprey packs are even heavier (and a lot more expensive) and don't seem to fit him as well. Any hot tips on other packs we should look at?