I wouldn't say that the ER-4P is missing anything under 70 Hz. Their bass isn't very strong by any means, but if you get a good seal with them, there definitely is bass. Whether or not it's enough bass for you, that's another question. However, getting a good seal isn't easy.
What annoys be about the ER-4P is the overly sparkly, jacked-up lower treble. If it wasn't for that, I'd still be using them. Their detail and imaging is second to none, and while they aren't very full, they're very clear and resolving. Definitely great to listen to with certain kinds of music.
I haven't heard the Super.fi Pro (what a stupid name), or the E4c for that matter, so I can't make any recommendations there. As always, I suggest that you a) listen to them yourself if you can before you buy and b) wait until there are some good reviews and comparisons of the new Shure and UE canalphones before jumping in on the bandwagon, unless of course you need them ASAP.