I'm looking at an IRO Mark V Pro frameset. I do think the the upgrade to 631 is worth the $30, but there is a possibility that I'll run SS on occasion (actually light off-road trails). So, my questions are:

1) Does the Pro have the rear bridge in the same position as the regular Mark V?
2) Does the Pro have the same rear tire clearance as the regular Mark V?

I'm not too worried about the front as I've got a fork I can use that will give me a small cross tire up front. I've also emailed and have been calling IRO since mid last week and have come up empty.