Are these TIG inverter frequencies good?

I seem to recall pulse frequencies as low as 20 Hz being useful, and do not recall any use for the higher end of your range, but my recollection is probably a bit out of date. What frequency ranges do commercial inverters use?

You just made me go and check the manual on Miller Aerowave, the most expensive $10,000 tig welder. Their frequency range is from 40 to 400 Hertz. Mine is about same, with the extra 550 Hz frequency value that might be useless.
After (and if) my project completes, I will have a welder comparable to Aerowave. Fully programmable, 8-92% cleaning/penetration control, etc. The only difference that I could see (with my limited knowledge and experience etc), is that Aerowave can have different EN and EP currents, and I cannot, plus Aerowave can do 300 amps at 60% duty cycle and I am limited to 200 amps, 100% duty cycle.
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