Yes, very true, Powder does rather mess up machinery of this sort, particularly ABC which loves to fuse into a globby mess when heated.
The last two national newspaper printers I visited in the late 90's used CO2, BCF & CBM (yes!) with AFFF or FP foam, and only BC powder and that in areas other than the big print lines. It was the only place outside steelworks & helipads where I've seen trolley mounted CO2.
It's quite correct to suggest changing the proportions used and what you can get away with depends on the exact polar solvent as some are not as destructive as others - i've used standard AFFF Spray on neat isopropanol fires to good effect, just needed to use slightly increased amounts and been aware that the seal breaks up far quicker so kept an eye on re-flash risks.
Angus Fire are the best source of advice, all my Foam & Polar solvent knowledge comes from them and their amazing amount of detailed free technical info (at least in the days before being absorbed by THEM) and have had the pleasure of visiting their factory for a day in the past and got to play with a variety of their kit.
Personally I'd still play it safe with AR-AFFF in the standard extinguishers as a minimum to ensure that you still get the benefit of post-extinction security & progressive knockdown as well as the non fire spill control benefit.
