I’m using a Disaster Area MIDI Baby 3 on my ‘minimalist’ board. Running the expression pedal thru MIDI, and leaving the 3 programmable switches for CC commands & sequences. It leaves the H9 expression pedal port open for EXP, EXP+ 1 Aux switch, or 3 aux switches.
The MC3 looks to be less of a learning curve for programming, and at least as capable (or more) than the MIDI Baby 3. The display is a plus, and 4 outputs (albeit with conversion cables). I would prefer the middle switch placement of the MIDI Baby 3 over the MC3, though.
With a 2nd H9, you might want to consider putting the two on different MIDI Channels. I believe you can send strings of up to 16 MIDI messages on each switch action, in either the D/A or Morningstar device.