Hi guys, an update, I did get a Keystep Pro -- after the above recommendations and some research into that, it seemed like a great fit for my uses.
@Ronin1973, per your point above, its not that I want to routinely do polyphony in Eurorack, but that I want to send arpeggiated chord info through (mono) Eurorack. Mainly the reason that I really enjoy chord to arp (mono) in my DAW and I want to be able to have the same fun in Eurorack plus the fun of Eurorack sound design. So the use case here is basically setting up a gnarly modular patch with plenty of CV shifting the sound, and then having KSP hooked up so I can enjoy playing the patch with powerful arp and other relevant live controls.
Wish I'd found KSP earlier, it seems like a great fit. Now I just have to find some time to dig in! This weekend hopefully...
Thanks all!