Diamond coating is fantastic but has the limitation that an ABC type (ABD?) can't be done as yet. The base material has to be heated far above the point where either brass or aluminium melt so it's only done on steel. However, it's quite possible to have a ringed piston running in a diamond coated steel sleeve. It's still in the development stage but is being tested on car crankshafts and transmission gear teeth (with very good results I might add ).

For ABC type model engines, I think the next thing will be the ceramic liners like Norvel use (and the replacement piston/liners that have been developed here in Australia for various engines). Actually the Norvel set up is near ideal in that there's no seperate liner because the cylinder is one complete unit somewhat like the old steel fin OS Max engines and several others. This means there's no barrier to heat transfer from the cylinder wall to the cooling fins.

Errr...and Ed, those Aussie replacement ceramic liners are available for that brand that escaped your attention