Check out the flipside 20L or maybe the 15. The quality is not as good at TT but they are pretty lightweight and easy to work out of and carry. I think I am going to get a 20 for hiking.
If you can tolerate a shoulder bag, the retrospective 30 is nice. Its a little heavy on your shoulder but the front pouches work well for filters. I love it but a shoulder bag gets heavy pretty quick and if you carry a tripod its really awkward after a while.