If coatings help maintain thermal stability by alleviating hot spots, the long term durability/reliability pays off though it might not show up in 'net' HP. Enbgine masters used to be but is no longer relevant to anything "real world"....e.g., 3 foot deep belly pan oil sumps, deck spacers with sleeves (Kaase actually tried to pass-off as "head gaskets" ) aimed at maximizing strokes/rod lengths, etc. Entertaining but on the whole useless to the regular guy because they never publish any of the really interesting stuff in any significant detail.

I'm pretty impressed with the fit and finish of the Mahle Coated pistons in my 414, I could have opted for the standard Diamond/Ross/JE's of scores of builds past but I wanted to try something different. And the pricing was attractive and they were locally (NC) manufactured. (Where's the American flag emoticon?)

Time will tell but companies have poured 10's of millions into the development of some of these coatings, I'm sure much (if not all) of the technology has spun-off/trickled down from NASA, it's not too far fetched to expect mass-produced ceramic based pistons and perhaps valvetrain components displacing metal based alloys in the not too distant future.

As for skirt scuffing well...you basically rely on "random" oil slinging to protect the piston and bore surfaces, there's a reason modern engines and race motors have strategic oil 'jets' and dedicated hydrualic oil control systems. No doubt you can do a lot more with a lot les.....if it's surgically applied and tested.