Yeah, there's no reason to run DMAME. Once DOS MAME became a separate special build and eventually was discontinued (if I remember right) there was no reason to use it if you hardware was of decent spec. Regular old Windows command line MAME (pre built in GUI) will support all your USB devices. My MAME v0.76 setup uses regular command line MAME along with GameLauncher and I use a PS Family to USB converter with it, no problems at all.
I have to run DMAME on the Pole Position cabinet since the computer is much slower and everything with the exception of video is on the motherboard. That and I like being able to just throw the power switch without shutting anything down, since there are no extra external controls outside the wheel, shifter and pedal to do such with.