People seem to have more trust in the 7 port engines and to be honest, I think the difference between 7 and 9 ports based on a same configured engine is hard to notice. But still so far I know no serious issues are reported with all 7 port models, I even know a guy who did put 7 port P/S sets in his 9 port engines after scratching pistons.

About the R2105 I had a lot of thinking about the non anodized head, many IR temp meters, even my FLIR can not read shiny objects. That can cause misreadings of the temperature.