Interesting debates here guys.
A few people have raised the point about 2h being easier and therefore allow more success for kinds at 8,9,10,12 etc, but my point was that with red balls and courts, orange balls and courts etc etc the disadvantages (ball bounce, less strength etc) are mainly removed. When taught technically well, with excellent attention to detail and adherence to the muscle memory principal from an early age (say 5/6 with a red ball) there will be none of the problems people have suggested in later life (players still chasing technical flaws etc).
Also, Dave brings up a great point that why teach something that 80% of pro's don't currently do, my question is do the pro's do it because they learned on a full size court with yellow balls and big racquets and had to deal with strength issues, high bounces, long courts and so on. The current crop of tour players wouldn't have come through mini tennis, so those problems would have been inherent in their development.
Maybe with mini tennis we'll see 80% of pro's with single handers in 10-15 years time?
Keep it going...