Nothing against Revelate bags, I have two and they're great bags, but have you considered a zipperless framebag. I had a custom zipperless bag made by Defiant Pack (
http://defiantpack.com/) and I really prefer the design. It uses water bottle mounts and Velcro for attachment and has a large top flap that allows for quite a bit of overstuffing. Because it's custom, it fills every bit of the triangle and holds quite a bit more than the Revelate/Surly Pugsley bag I replaced due to a broken zipper. The bag loads from the top, so it's one big pocket without dividers, but it's custom so vertical dividers can probably be added and it does have two pocket on the top flap. Also, at $160 it's actually a bit cheaper than the Revelate bags. Here's a photo showing the fit and flap design.