I was pondering this the other day, specifically why I never see any high level falcons doing it really. It works around 70-90% against spacies, and I think similar percents against falcon as well. I've even had it connect against shiek before but I have no idea at what percent or if it's even a true combo, so don't quote me on that. It's got more kill power than SH knee and it's much easier to land, so I don't see why you wouldn't go for it. On top of that, it works on all DI but down and away, and there's enough hitstun on uair at that percent that you can react to the DI away with an easyknee or nair/uair -> knee. Anybody better than me at melee who can shed some light on why this setup isn't utiluzed more often?