Hey Goolager,
I have had one of these sling packs for almost 2 years and think it is great. Just watch how deep you wade with it on. It carries a lot of stuff and is easier on the back than a vest. The only down point can be finding things unless you are very organised but this is the same with most bags. It easily takes 2 large C&F designs fly boxes, a couple of reels and other usual stuff for fishing.
Hope this helps.
Mike