I've bought a couple Prime M carbon fiber shafts from BeCue. They are 12mm diameter and 31 inches long. I prefer a slightly smaller diameter and conical taper, since my fingers aren't too long and it fits better in my bridge hand.
The Prime M isn't quite so stiff as a Revo also.
EDIT: I'm also using your Very Soft Ultraskin tips, which work well with this shaft.