I have come to the conclusion that no matter what the drive, within reason, a look at stepper manufactures torque/speed curves is the most reliable indicator of what can be expected and they all look pretty much the same.
I have several Parker OEM 750 drives with many features yet they do not do any better that an inexpensive Allegro SLA 7044m based uniplolar drive I've used for several years.
I have not found steppers inaccurate or too slow, but I have never been interested in super fast G00's or air machining