I think I've found a way to dirty up that corner vortex some more.
After the blocked crossup F3, you can do step 3(2), right? For two bars, do step 3(2)~DFMB. If it hits, free combo back into the corner; if not, you're in range for a high/low mixup with B1U2, B2, and F3 again. B1 and F3 can send them back into the corner again for free (I've confirmed that you can B1U2, dash under, 1, 323... but walking under doesn't seem to work), and B22 can send them back to the corner for another two bars.
EDIT: Whoops, forgot the important part. Without knowing cancel frames its hard to theorycraft, but 3~DFMB beats both Flash Uppercut and Lex Corp Charge reversals, but Kryptonian Crush and Batman Parry will beat it. So not foolproof, but still a pretty good option to continue pressure. Backdash seems to work as well, but pushblocking doesn't because MB B/F3 beat pushblocks - I never knew this!
EDIT AGAIN FOR MORE DIRT:
When people sufficiently respect 3~BFMB and are looking to block it, you can start throwing in 3~DFMB dash cancel B1U2 to catch them off guard. It's kind of hard to execute quickly (though still easier than SF4's ridiculous FADC controls) and is a pretty weak frame trap (can't get past flash upper reversal), but I reckon you can catch people off guard with that. DFMB dash cancel still seems to be safe against Flash Upper if you just block after and don't press buttons, so if people starting throwing around unsafe reversals when you dash cancel, you can block and punish them for it as well.
I'd love to see frame data for cancels and dashes, I reckon DFMB~dash cancel could open up a whole new bag of tricks, maybe. Or gimmicks at least.