I don't think it really matters what other people's experiences have been - there are people that win at micro cash games, there are people that win at micro SnGs, there are people that win at both and there are people that win at neither.
The fact that one or more people win at either one has nothing to do with whether you will win at the same one. Whether or not you're going to win in SnGs isn't really affected by whether you win in cash games*.
Pick the game you enjoy the most, study it and work at it. That's how you get to be a winning player. There is no magic bullet.
* an exception: if you suck at poker in general you probably won't win at either.