Motor commutator noise

I am trying to reduce the electrical noise from a 12V 5A brushed dc motor, driven via a pulse width modulator.

Much as I would have fun trying various configurations, I would also like to get the thing sorted asap.

So having googled around a bit, and thought a bit, I get the diagram on the right, with 10nF caps in three places, a couple of 15mF chokes, and an RC damper.

Part of me is a bit itchy about putting caps straight across the commutator as I was taught that capacitors directly across switch contacts causes erosion – am I wrong in this case? Or should all the caps have 10Ω in series – then the damper might not be necessary.

Also, if I put a reverse-parallel Schottky across the motor terminals (as well as the one in the modulator), will that reduce rfi by cutting the current in the connection loop, or increase rfi by messing with the voltage waveform in the leads?

By the way, the leads are twisted (or will be).