Ok.. two things...
I tried another burn with the PRODISCR03 - the drive got to the finalizing stage and simply wouldn't stop - redlight was on, drive was clicking occasionally and every now and then would speed up and then slow down. It kept doing this.
I cancelled the burn and later used the EEPROM utility to reset the learnt media data. I tried to reburn the same stuff to the PRODISCR03 and got the same results - wouldn't stop finalizing.
This PRODISCR03 stuff is VERY strange.
One thing of note - if it isn't aready known - is this media is inkjet printable to the hub. Since I've had one semi-decent burn out of it, I shouldn't think that means anything. Just thought I'd mention it anyway.