Short answerr, no G-Rex is not a deepfryer for BPPC cards, it's a peice of amiga hardware that connects to the BPPC. ;-)
Bur seriously, I would never buy a G-Rex since they have a tendancy to fry them selves and sometimes taking the BPPC, motherboard or both with them in their fall. Many of these fatalitys might have something to do with the louse connection for the G-Rex, I dunno. To mee it all seem like a very poor peice of hardware rushed on the market at it's time and now long forgotten and still lacking in drivers, support and/or warranty (yes even NEW boards are sold without warranty).