Feint chains grow old really fast. Like, for serious. It'll stop working after, like, 4 or so games in. And then after that, your opponent's gonna realize that every time you cancel a chain, it gives him enough time to air dash straight to your face. Or, at least, slip past the point where a chain isn't an effective zoning tool anymore.
Also, if your opponent blocks any D, don't fly in. 9 times out of 10, you'll get hit out of it.
214D stance is like one giant mindgame. Throw it in a blockstring from time to time if you know your opponent's going to keep blocking.