hey there Mday. yes, I have a Iomega 12x flashed to a plextor (some of u may recall that Compusa special a coupla Spring seasons ago)
and this model does support overburning. I have in fact enabled overburning in Nero, and i've run through various little options within Nero. I've also read what I could find on the Internet about this issue.
1 file, >700MB in size, use 800MB cdr media = cannot burn with Nero (far as I know and tried)
11 files, each 70MB in size = 11x70 = 770MB total, use 800MB cdr media = can burn with Nero.
and technically, this is not called overburning, as a website puts it, overburning is burning >650MB onto a 650MB rated cdr.
Burning >700MB onto a >80minute (700MB cdr) is oversized burning (I think they called it).