I seem to have come to a dead end for the time being. Posted bits of this in a couple of places, but thought it probably worth pulling it together here...
Purchased Mini10v in the UK on September 23; set up showed it to be running A07 BIOS.
Tried the 'straightforward' installation of SL through USB stick, which ran smoothly to the point of freezing on start-up. No messages.
Tried the software BIOS downgrade (/forcetype and all that) which again looked promising until it pulled out with an "incompatible version" message.
Took the drive out and installed SL directly from the Mac following the method posted for A06. All good to point of boot freeze, this time with a handy "no entry"-type graphic above the apple.
Anyone else come across A07? Looking around, seems like just me at the moment! Glad of any thoughts.