This is what I use and i love it. I never use it as a chest pack only as the strap is uncomfortable on the neck. but it never rides out of position or slides up. I also wish the backpack had a bit of a bigger opening, but it is a very small problem.
I still have my vest but never use it unless I want to wear something while floating in my toon.
I highly recommend the double haul.
http://fishpondusa.com/doublehaul.cfm