I've looked at this rack a few times, but I have some questions first so I might be able to offer some advice: When you say "a lot of chordal voices," are you referring to the chord mode within Plaits? Are you planning to add other oscillators, envelopes, and VCAs so that you can sequence those as chords?
How far are you looking to go with this? If you are planning to sequence with the 0-Control, Hermod might be a bit overkill with a rack this small, but it's pretty common to expand beyond a first small rack so it might make sense in the long run. I'm just not sure what you are envisioning long term.
If you are ok with using external gear, why eat up all of your rack space with the Subharmonicon?
How much prior experience do you have with synths?
Let me know what your thinking is on these, and I'll help if I can.
Have fun and good luck!