I've been using a large Acorn bag for a couple of years now, and have been pretty happy with it. I like the idea of supporting a cottage industry type business, and while I have not used a Carradice or other, similar bags, the quality of the Acorn seem to be right up there, and the price is comptetive as well.

The Acorn does not claim to be waterproof, but I've never had a problem with my stuff getting wet in moderate rains. The leather straps and buckles and not the most conviniet access, but the are secure, and are part of "the look"

I'm happy enough with it I plan to buy a front rando bag from them soon.