Front intake Vs rear intake

Simpler maintenance - FI
Easier to cowl cleanly - RI
Smaller crankcase volume - RI
Shorter crankshaft - RI
Smaller diameter crankshaft - RI
Lower internal drag - hmm

More parts a turning, but the bearing balls running slower in the races.

I would imagine the engine designers could add a dozen more considerations to the list. But what if the engine did not have to drive the rear rotor or drum?