Been having fits with starter drives eating ring gears on my'07 Dyna.  Well, for those that have had similar problems I'm thinking we finally found the problem.  The All Balls starter clutch shaft restricts the gear engagement by 1.5 mm.  That's enough to keep the starter gear from fully engaging the ring gear.  (See Photo)  We found this by comparing the travel between an '09 Dyna starter clutch and my All Balls replacement starter clutch.