Meh. Timing issues become almost irrelevant in a world where consoles have dynamic clock scaling, deep sleep modes, etc. Games are usually not written around specific timings anymore.

Bugs and errata can be a concern (I think I remember some issues regarding PowerPC atomic instructions misbehaving on the Wii U for example) but I would expect them to be fairly minor compared to the whole work of REing a custom microkernel and its associated services.