Vortex Sound Research

I am looking for some 80's FM for my rather cheap jamming setup and I am considering a Volca FM or Korg 707. The obvious choice is the Korg and I was already settled on buying it in the near future but then I learned about the Korg. The Korg is just as expensive on the used market as a new Volca and has a keyboard (I don't have a midi keyboard). It also has a higher polyphony. The downside of the Korg are bad presets. But if I understand that correctly the sound engine itself isn't bad. An other downside is that I can't use dexed presets with the Korg (?). Also there are not much presets around.

So, is the bigger keyboard and polyphony worth the time making own presets? Am I missing some other pros or cons? Are my assumptions correct?