Thank you so much for your answers!
I have then come to the conclusion that I will live with the steppers and speeds I have for now, and when the time is right to upgrade, servos will be the only option.
There's not much I can (or want) to do about the gearing, but I do realize that if I got it down to say 1:3, I would be where I wanted to, speed wise.
I still think/wish i should be able to see some higher zero-resistance speed with the motors I have, but "investing" in a 56V power supply would also mean ditching the whole HobbyCNC control, which is for another day.
Thanks again