just trying to get the best deal/pack
This is going strictly from my experience, BUT I have not bought a new pack in over 7 yrs.
1. No pack is water tight (not that I have even seen in actual use anyway.) Like I said, I have not looked at packs in years so there is prob better technology avail than I am used to using/seeing.
2. And IMO this is the biggest factor in the equation of a pack. Take the $$ out of the game. How expensive a pack is, how many support bars are in the back, how much padding blah blah blah is meaningless if it does not fit you and fit you comfortably... Go to the store, try them all on. Find some that fell good and then load them down IN THE STORE, and shop around the store for a good half hour to see if they still feel the same way. Then when you bring it home, load it down and wear it every time you go on a walk or a hike to get used to the pack to figure out the adjustments. You don't want to find out on day 2 of a 3 dayer that the pack rubs in one spot really bad or something...
Don't discount external frame packs. I have a cpl of both and use my external frame packs just as much, if not more than my internals. They are not quite as comfortable but with the frame holding the pack off of your back they are much cooler IMO. My back sweats like a mo fo in the summer with 35-40 pds of stuff slapped in an internal then strapped to my back.