I've used many motors with the G540 that should have been used with a G203v or other 'high powered' Gecko drive. I limited the voltage to 48VDC. I limited the current to 3A (although I could have gone as high as 3.5A). Then I ran the motors to see how well they performed. Most of them worked very well for the application that I needed - CNC router. In that application, high speeds are not necessary - even when the motors are geared down 3:1. For instance, with a rack and pinion drive having a 1.25" diameter pinion gear and 3:1 gear reduction (via a belt-drive), 750 RPM gives me 16" per second, which is more speed than I can use in that application.
Oriental Motors PK296B2A-SG3.6, PK296-F4.5A, PK299-02AA and PK299-F4.5A have all been with the G540. All worked well after I 'crippled' them by limiting their voltage and current to fit within the boundaries of the G540.
I've also used those drives with a G203v. Again, for my application, either the G540 or the G203v would have given adequate performance. The G203v required the use of a PMDX-122 break-out-board. The G540 was used right out of the box.
For those applications that are price sensitive, if a G540 can drive the motor fast enough with enough torque to do the job, you've found a solution. If you need more speed or more torque (assuming that the motor had to be 'de-rated' when used the the G540), you always have the option to replace the G540 with some G201x or G203v stepper drivers and a break-out-board.