I've got a
M-Rock Olympic sling bag for daytrips and it's been really nice for the few weeks and trips I've had it for. I carry my K20D with either the 16-45 or the 28-75 attached and then 70-300 for longer reach. In addition, I can get lens hoods, lens cleaning supplies and a couple of filters in the camera compartment. It doesn't get too heavy with what I listed and it's got a great back panel that allows for air flow down and around your back. I was out in 90% humidity and 90 temps and I didn't feel like my back was on fire. It's a tight fit if you want to carry personal items but if you stick to minimal supplies you can make it work, like small wallet or money clip with cards, sunglasses and mobilephone. Haven't needed the rain cover yet but it seems to be useless because then you have to take the bag off and carry it by the handle. I may look for a cover that can just slip over the pack when it's on though. Overall it is comfortable to carry if you don't overload it but for hiking you would be better served with a backpack.
I looked at the
ClikElite Compact Sport pack but it was rather costly compared to what I was willing to spend. Looks really comfortable and light but haven't heard much about these packs. It can hold a hydration bladder for hiking also and has attachment points for accessory pouches and bags. Cool color too!
Good luck and hope you find a nice bag. It's the never-ending journey!