I know this is a mach forum - but have you looked at emc2? It will do closed loop with a minimal of hardware. (pid and motion within the pc)
http://www.linuxcnc.org/
supported hardware
http://wiki.linuxcnc.org/cgi-bin/emc...orted_Hardware
emc2 uses 'dumb' hardware that really only counts encoders and outputs pwm or analog signals.
sam