One thing I found extremely helpful when I bought a new pack was having it fitted & adjusted by the sales girl at my local MEC. While she did do a great job at pointing me at a good bag for my needs at a good price, it was the fitting that I think makes the real difference.

They have bean bags or something that they use to load up the pack with weight and then go through all of the adjustments to ensure not only that you have a pack that is the right size for you (many come in different back lengths, for example), but that you leave the store with it set-up and ready to go. This includes finding the right shoulder point adjustments, etc.

If you do end up looking for a new pack, I'd highly recommend finding a store that has this level of service (I think REI does this in the States).