--------- Problem number 1: Rob and CJ have drives which do not like any other layer break address than the one which is their default. Thus growisofs and cdrecord fail if their automatically computed layer breaks get set. The remedy is to enforce the drive's default layer break address and override the programs' computations. (This would mean that cdrskin has no problem with those drives. I would appreciate confirmation.)
There is also possibility that some/their units require layer break to be set and to be set to value embossed into media information zone. I mean not setting layer break might fail too, just as setting it to non-default value. I know it sounds crazy, as unit knows where to set layer break, and shouldn't need a reminder, but stranger things were observed... Cheers. A.