AFAIK, no, not yet. If the Mostly Stock ROM that I'm currently running gets updated, it will probably be flashable without wiping. When I went from plain rooted stock to this ROM, I didn't wipe anything, and it kept app my apps, data, etc. as they were. I'd like to see it updated, but even after asking on XDA, I don't know if it will be. We'll see, I guess. I got the update notice today, so I'm hoping to see something in the near future -- or at least a way to disable the update notification from popping up periodically, since I can't actually apply it while rooted.
Edit: For whoever may be interested, xBTx has indicated that an EL30 version of the Mostly Stock ROM should be coming soon. Once it does, I should be covered -- I can just flash that over my current version of that ROM.