Kevin, for your rack IMO Intellijel Triplatt (or MI Shades) would be a better choice vs. Vermona Amplinuator. Triplatt will be more versatile and also less HP. Having something like Triplatt or Shades in your rack is IMO another "no regrets" type of choice, it will be useful on many many patches. I would have one of those in basically ANY rack setup. Furthermore, if you get to using more complex CV modulation, something like 4MS SISM or Tiptop MISO is super handy; those are basically suped-up Triplatt. But Triplatt is super useful and small.
You already have Erica Techno, so that already gives you Mixer Lite, Mixer and Stereo Mixer. That will give you a good number of basic mix channels and should handle your immediate needs IMO. Why bother with WMD Performance Mixer when you already have those Erica mixer units? Yes WMD PM is very good, but it is big and expensive, and I don't see a need for those in ADDITION to the Erica mix modules you already have.
I've read more closely the posts above, now thinking PNW may or may not be a good fit. It's a great module, but I don't know that it makes sense given what else you have. BTW if you need to coordinate a lot of different sequencers the PNW with its 24ppwn expansion plus a mult would be a good way to sync everything; that's what I have to sync my many sequencers. SO my suggestion is PNW goes into your "maybe later" modules.
Hope this helps. Good luck!