Hi Pat...
This part of the Modulator is really interesting and is worthwhile spending time reading up on....etc:...
If you play around with the Tonnes Calculator you will discover how the number of poles / cutoff frequency / loading etc: can have on your transmitter overall....
But bad things can happen without you knowing or realizing etc:
I don't use Motor Controllers for any of my PWM Generators .... for 2 main reasons...
......Sawtooth waveform
......Free running oscillator
My Generators are all Crystal locked divided down and pickoff 250Khz .....there is a reason for that frequency but will leave that for now....
Just say you decided on using Jons LPF with a 45Khz cutoff....and notching out the PWM sideband....
Running 1500 watts PEP all good.....but just say at some temperature your Motor Controller went frequency wobbly.....
won't hurt the motor..
Your only defence is your notch filter now ineffective and relying only on the 40db attentuation of your filter....
Although the chance of this happening is low .... the fact that it can happen is why you design your filters.....
Hope I have not rattled on too much and Jon not saying your filters are a poor design
Thats all....
Wayne