Yeah, repitition is hard for everyone to break. When it comes down to it though, this whole game is about using something until they figure a way around it, then countering their counter, so that they are scared to counter the original tactic.
Siegfried has a lot of different mixups and a good amount of places where he is at advantage. Recognizing their defenses and reactions post a

A, b:4 etc.. changes the flow of the match. If you can lock them down there, you start taking control of the match.
There is obviously a ton of things post-a

A:
3B (duh)
3A, takes care of all side steps.
2A+B obviously only if the are finally trained to stand there.
Stance Dancing
22_88B
iWS A (A on CH check)
Stance cancel throw
etc..
All of the options post a

A are good, especially at the tip range of a

A.
Range IMO becomes the most important aspect of Siegfried's game. When you can keep them out, it not only keeps you on the offense (well, defense i guess =P) but it's also incredibly frustrating on the other side (unless they are patient, then you probably have a good player playing against you =P)
Staying at tip range with Siegfried is gross and it makes you feel warm and fuzzy inside. :D
P.S. you've been around since SC2 right? I'm pretty sure I recognize your name.