it's hard to do some stuff on pad because your thumb can only cover so many buttons
it's why people use punchx3 and kickx3 macros so much, because that'd be tough on any kind of pad
also for kara throws it's way easier on stick. like Chun's kara throw in 3S is medium kick and throw all near the same time. that's three buttons and tough to accomplish on pad.
also really fast combos become easier on stick sometimes
that's all I can think of
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http://www.youtube.com/watch?v=npHDxSvwCE0