Then you did not master it.
Uh, sure. Ignoring possibility of human error every once in a while, if you don't mess up bad
enough then you should be fine. Just remember not to use too many of Sheik's pummels or you'll inadverdantly allow a ground break. Also be sure to pummel extra carefully against Reflex.
You also missed a few posts about stalling the clock if your ahead. (Especially if you somehow have a stock advantage).
See, this would normally be a
great thing, but you're also running the risk of allowing Wario to charge his Down+B this whole time. If you don't mess up, and you manage to stay out of harm's way for the rest of the match, then it's fine. Still risky though.
Unless the frame window is something stupidly small (1 frame) it can and will be mastered by someone. Difficulty is not relevant.
Difficulty can have an effect on overall consistency, but otherwise yeah, difficulty's not that big of a matter.
Also it could be used to get an extra 15-20% for a guaranteed KO, you don't necessarily need to do this for 100%+
>_>
Well, I suppose if you land a grab just a
little earlier than you should've then you can go for it.