I used a custom one (no insulation and resized) on the Tour Divide to hold my tent poles and stakes. Worked great except for mud clogging the zipper. The only thing I'd change is to get the zipper on the non-drive side. I have a triple chain ring and I sometimes bash my knuckles on the big ring's teeth getting stuff in an out.
Josh is really great to work with on custom stuff. I also have a custom frame bag and Stem Cell from Broad Fork.
I'll keep the zipper on the non-drive side in mind thanks for the info!