I think in America they race a equilivant class to zapcats with honda 45hp outboards, so performance with the 50 must be pretty good.
I'm sure it was 45hp, though doesn't seem honda make it anymore... Maybe its just avaliable in the US.
It wont be as lively as with the tohatsu 50, but it would still be good fun. The only problem is if you flip it, starting a 4 stroke again would be much more difficult than the 2 stroke.
Edit: I think I saw a video and website racing 'dux' boats with the hondas, but I'm not so sure now, was I dreaming???