I should have elaborated more on the sh101 vibe, I know the Atlantis isn't an exact clone but that's sort what made want it more from the demos I've heard. I appreciate that it can get in the realm of the 101 but can do much more. If I were to pull the Atlantis out of the rack I would probably go with a Malekko Manther. That box is wondeful, and what inspired me to pair a wavefolder with the Atlantis.
I do like your idea of potentially replacing the Atlantis with a Rainmaker though. How does Rainmaker compare to the Strymon Magneto or the 4ms DLD?
As far as the mutant brain with the digitakt, is there any reason to go with that instead of Yarns other than the HP?