Wally,
As you know I'm not a purist nor a racer. I'm a pleasure oriented sailor. I  
have never found a negative side to the IMF. In fact, most people on the lake  
are in awe and envy of me every time they see me use it. They marvel at how 
easy  the R22 is to sail compared with their boats.
As for the additional weight up top, I counterbalance with enough rum on  
board that it doesn't matter.
 
Rummy