I have gone back and forth between backpack & pannier. But once I started using my Deuter AC Lite 25 http://www.deuter.com/en/products/34...e20_08_DEU.php and I haven't looked back. The pack is designed not to sit against your back, using a mesh pannel and internal frame.

It is great for me, my old pack gave me bad pack sweat. This pack give some but nowhere near as much as a regular pack.

Basically the only time I use panniers now is if I am going to be very overloaded.