Thanks for all the advice, it's so hard when you can't actually get your mitts on them to compare.
I am no nearer a decision, any other suggestions will be welcome. I am thinking of ordering a UP as they are not expensive, just to get the feel of carrying one, and using a bladder, then making a more informed decision for the next one if necessary. I like the sound of the OMM....
Having a bash at an ultra next year, and need to carry a minimum of 1l of water, emergency first aid and wet weather gear (hopefully won't need it!)
Any recommendations for a ladies backpack, have looked at Salomon agile 12, camelback 2l but completely no idea. I am on the short side but quite wide(!) and tend to chafe quite quickly (ouch!) I need to be buying this relatively soon.
Look forward to hearing from any/somebody
Grumpycow ( I'm not really but don't tell anyone!)