HRC did indeed make two HRC PGMIII units. One for pump fuel (30400-NKD-700) and one for avgas (30400-NKD-840).

I've not had the pleasure but I've had info from the HRC men that "much power coming, but very easy broken". Read that how you want.

Another good indicator of something trick is the code. CI605E is definitely not a production ECU number. CI605 and CI605B yes, but not E.

These boxes are still available (last time I checked) but they're bloody expensive! No idea how much you paid for the box, but I reckon you got a good deal.

He mentions something about detonation control. This may be the same as NSR250 F3 PGMII and also RS250 PGMII, in which case you can clip wires to retard the ignition timing. The Yamaha TZR250SPR SP kit CDI also has this function for the choice between avgas and pump fuel.

The MC18 PGMII also seem to have the same wire that's hidden in the F3 box, but when clipped it seemed to make no difference in my test.