any issues running a counter rotating engine for a single engine use?

[spareparts]

as far as I know, they all(CR units) use the rear most gear as fwd gear rather than the front side gear as fwd(confusing isn't it). The counter units use flat torrington bearings to support the load rather than tapered bearings, OMC units didn't really change that much as they allready use teh torrington bearing. The flat bearing is supposed to be better than a tapered roller. I do know they are a pain to set up, and they have closer tolerances, I think incorrect set up may be the main cause of issues with them