Originally posted by ben_leg Thanks for your reply, unfortunately i can't really go on a day hike or ride 100km on my bike with a shoulder bag.
How much time have you spent at the local retailer? I found that packs and slings were especially hard to buy without trying them. Granted, I am 6'3"+, and that may have something to do with it. I've been able to buy smaller bags over the internet, but when it came to larger packs--no joy.
What few web sites can tell you is how that pack fits your back. Camera packs often do not have the adjustments which are standard on a decent pack. Many packs have no waist straps. To get a camera pack with full suspension and adjustment is often quite expensive. I've seen suggestions, with which I now agree, that if you have a pack that works for you, that you look for a liner to replace your sweater, rather than replacing the pack with something that may be inferior for hiking. (While I was posting this, I see Bdery said the same thing)
Finally, I found that sling packs with waist straps can be a much more viable option than they appear without trying one on. (I was a doubter of hikes with slings until I tried and bought one). Still, I am also a cyclist, and I wouldn't ride 100k in that sling or anything that wasn't designed for cycling.
Even if you have to pay more and drive more, get to a store. Buying a pack which you will wear while engaged in some other activity without trying it on is like buying athletic shoes without trying them on.