@dangermouse
Resoldering BGA's is probably not for everyone, I doubt any of the guys that fix Amiga cards has any equipment to do that.
I'd risk and send it to ATE, eventhough never saw a report from any Amiga user that has used their service. Might be expensive too, but IIRC it wasn't that expensive comparing to the prices at AmigaCenter and specially considering ATE has special equipment to deal with BGAs. One problem though is that they problably don't know what an Amiga is

Or you might end up with a screwed up card instead of the 68k side working but I doubt it, after all they're just resoldering the PPC.