This is a very good idea. Just a note on the Polemos conversions though:
ESR gives the following conversions:
ESR 6-7 / Polemos Elite
ESR 5 / Polemos Veteran
ESR 3-4 / Polemos Trained
ESR 1-2 / Polemos Raw
However, Polemos only uses the three basic ratings of Veteran, Trained and Raw. Elite is an additional characteristic, so you have Veteran-Elite, Trained-Elite and Raw-Elite rather than “Elite” by itself.