a lot of what you can get out of a stepper motor depends on a lot of factors. the machine mechanics are a big part of this. you can gear them to to operate in a better place based on the torque speed curves to get more performance but until you get your machine built it hard to say.
the one thing that is important on what you can get out of a stepper motor is running them at the highest rated voltage you can get out of the motors and drives. so the cheap motors and drives are probably rated at 50 V so i would use a 48 V power supply if this is the case.
so when you decide on the drive mechanics all this will come together when you start tuning things.in general the faster you run a stepper motor the the more power they will loose. they do best at lower speeds and drop off like a stone the faster you run them.