It’s looks like a fun setup. I think you can make shitloads of awesome sounds with that. That being said I think there’s still a couple of things to consider.
I don’t see how you would use the stereo mixer, and the Atlantis has a built in vca so maybe you don’t need the other one.
Another thing I would consider though is if you really need a sequencer when you have the midi interface. In such a small system you could get a lot of awesome stuff instead of a 600$ sequencer. Like wave folders, filters, delay, sampling another osc etc.
also consider other midi options. Maybe you don’t need all the stuff that yarns is probably capable of (I haven’t checked it out) it’s probably awesome, but also quite expensive. I use a Kenton that does a lot of stuff as well but I’ve never used it for anything but trigger and cv, and I just hate the menu diving. I’m likely to sell it for something more simple and less expensive