I've been using eding cnc's CPU5B & Software which is very useful and Damen CNC sell connectors that allow you connect directly from the PCB to Driver, (Greatly reducing the amount of wiring)

Another advantage of this system is that the error reporting from the servo drives can be easily fed back to the cpu.

I'm using these and if you get missed steps the drive just shuts down, so if you dont feed the error back to the control board the other 3/4 axis would carry on regardless!

I'm not sure how easy that is to do in mach, but its a defo if you want to get best use from your investment in the servo drives!

website links :-

http://www.edingcnc.com/

http://www.damencnc.com/

Also a good time to buy from the continent with exchange rate being what it is...

Regards
Andrew