I wanted a sling pack because when I started fishing, I had a canvas satchel. I got a Patagonia atom sling, which, from what i could tell, was the best for me of the bunch.
I think it would help to get some organizational advice on these things, first. I switch things around and am not sure if there's a better way.
I feel compromised with it. I got it for limited flyfishing, like an evening sulfur hatch. You need only so much of specific things.
Like so many people, i have specific things I want on me; specific items, ways I do things and things I resort to. Those things are in different places in a pack. You need duplicates of things. Turning the sling around all the time gets old. I don't like reaching back to find the securing strap so that when I bend, the pack doesn't slide around to the front. Every time you need something, you have to start digging. Unless there is a different way of doing things, I find I need at least 2 sets of nippers, front and back for all the things I do with them. Almost clamps too. It's cooler, but its still not like you're standing there with just a T-shirt. it's still hot on your back and around your neck. And if you hang a net on it...Holy $#!t, you would have crap jangling around you like a walking christmas tree, hitting you; just a mess.
My biggest problem on the inside is that I want better places for my tippet spools. I suppose I could pay for another tippet-hanging doo-dad, to dangle and tangle and annoy. I need better places for storing my nymphing stuff: indicator and shot holder. With the slings, you are supposed to just 'jam' (I'll say ) stuff together. sure , they hold what you need, but you're sorting through stuff to find what you want.