After a few gallons of fuel there should be minimum wear. I think the waste oil is fine to recirc BUT, not post venturi. My methanol engines run great recirculing crankcase oil pre venturi i.e. into the velocity stack with no noticeable change in running behavior. The methanol OS 4 strokes I've run with factory recirc into the intake tube ran noticeably better disconnected, venting to atmosphere instead.

I've not tried recirc on a gasser but one thing that I've noticed running gasser 4 strokes is it appears there is a significant reduction in overall wear. Better oil? Inherent lubricity in gas? Not sure, but one thing for sure, it's many more hours of run time between valve lash adjustments.