This is really two questions: will the drivers work with the PMDX-424, and will the drivers/motors work well in my machine.
The PMDX-424 works with pretty much *any* stepper driver as the interface is pretty standard. The stepper drivers should have a step input (also sometimes called "pulse"), a direction input (sometimes called "pol" for polarity) and a "common", which is usually either ground or +5V. Some drivers have "Pulse+" and "Pulse-", "Dir+" and "Dir-" (or maybe "Pol+" and "Pol-" for "polarity) in which case the "-" terminals can be tied together and connected to the PMDX-424 "COM" terminal. The "Pulse+" goes to the PMDX-424's "Step" terminal and the "Dir+" goes to the "Dir" terminal. Then configure the PMDX-SmartBOB plug-in to output "Ground (0V)" on the "COM" terminals.
Some drivers also have enable terminals. You will need to refer to your stepper driver manual to see whether you need to connect these to anything, or can leave the un-connected to enable the stepper driver.
The issue of having the motors and drivers "matched" pertains more towards what kind of performance you will get from the machine. I'll leave it to Steve or someone else to address the motor size issues, though it would help if you could tells us a bit about your machine (i.e. is it a 4' x 4'x router like the example you quoted?).
Bob
