Undo is unfortunately not an easy thing to add once the plugin structure is complete. Still, I have high hopes we could do some sort of it in a future update. Not in next Dimension Pro though, that one is already closed.
There're a couple of components in the slip for the Dimension Pro update. One of those is that we introduced a significative amount of useability, sfz format and performance enhancements in the Rapture cycle, and after releasing Rapture it was clear by everyone here that those needed to go into Dimension Pro as well, even when they were not originally scheduled.
As a consequence of this, Dimension Pro users will get those as part of the upcoming update. This will make a much better experience for users with both Rapture/Dimension Pro in terms of common interface gestures, etc. There's a nice load of small, not press-release-tagged things in the update.
There's another component related to the new platforms, formats and machines (ProTools 7, Universal Binaries, Intel enabled Mac) we're boarding: those components are really new, and scarce. I was in Boston beg-mar, and I wasn't able to bring my Intel enabled Mac by then. Fortunately now they're in the office, up and running.
I know what you're thinking right now: "I don't care about Intel enabled Mac". Believe me, you do. Even if you're a "I-Love-Bill" soul, you do want to have more Dimension Pros all over the place. That'll give you more third party support, more banks, patches, programs and samples, longer product lifetime.
Anyways, we're almost there, testers are trying hard to make it fail.