Roger,
Based on the experiences of R22 owners that I am personally aware of that  
have the four stroke engines, they are not reliable. The three that I know are  
Alex Bell, Claude Cox and Dan Hope. All three had the 9.9 of the two popular  
brands and all three have had and are still having problems with them. Three 
out  of three pretty much tells the story as far as I'm concerned.
 
Rummy