Bob V.
Not sure what you are doing so differently but it seems most guys at the gold cup were having their alky animals rebuilt in sr every national or two to maintain peak performance. I didn't rebuild my gas engine and raced it 8 total days and it ran just as well the last race. I like it much better than the 206 or clone because it is much faster. Unless you ran them back to back you really wouldn't notice much performance from an alky engine to the pro gas. In road race where they are always wound up you probably wouldn't even see a big time difference. I do wonder though how the engine temps would be on the pro gas in enduro? I know many at kershaw gold cup were near 500 degrees although I was around 430.
Anyway, for me personally I prefer the pro gas engine over any other. Much cheaper for me than the alky, better reliability and quality control than the clone, and a lot faster than the clone or 206. My second choice would be a 206. The only downside for me on that engine is speed otherwise it is an awesome package for racers to start on.