I think that separate controller board and inverter with power supply is the only way to go. I recetly began looking into PMSM control and the differences in motors are too big to use one MCU/power stage combo. On eBay there is plentiful of used servomotors from industrial machines (probably from modernization/retrofit), which are quite cheap and for us hobbyist still good enought. And the difference in DC link bus voltage of inverter stage is huge. The motor I bought has the original driver using 670V DC link, some Fanuc ones use about 100V and so on. Also there is difference for power resistor for dynamic braking and other aspect of design that make me think that ability to differentiate the inverter is only way to go for general purpose driver.