Got your PM. Will look at disecting the files soon. I will reserve judgement until after I've had a look through that. My suspicion is currently leaning toward just checking the device ID in the BIOS (as opposed to only the straps). On a K series the cards have UEFI crypto stuff in the BIOS, so it is more difficult to change the BIOS other than the straps (unless you just completely rip out the UEFI headers and the trailing certs and other garbage). Since most of the hacks focus on the device ID (as opposed to what the BIOS things the device ID is), it is possible this is overlooked.
Nevertheless, a Quadro BIOS should be very easily modifiable to suit using the existing tools (or just manual hacking) - mainly just a case of tweaking clock speeds and timings. In some cases it will work out of the box: e.g. my GTS450 cards work just fine with a Quadro 2000 BIOS. Unfortunately, this does not restore the missing GL functionality. There are three possibilities here:
1) That functionality is laser-cut out of the GPU - no hope of restoring that.
2) Pin shorting on the GPU to disable the feature (e.g. caps across pins - plausible, but I've not been able to establish a pattern here, all GTS450 cards I have had were mutually different in that regard, and different from the Quadro 2000 as well.
3) Secondary firmware somewhere that initializes an FPGA somewhere to do the normally crippled GL stuff properly.
My suspicion is that 1) is the case since the Quadro and GeForce GPUs have different part numbers stamped on them, and this likely happens before they are fitted to the PCBs.
I don't think there is a Mosaic utility for Linux, but I could be wrong - you can set up multiple displays using xorg.conf anyway (e.g. when you're using an IBM T221). I don't remember seeing any driver options for adding spacing between monitors, but I haven't looked. I certainly haven't noticed any difference in features between a real Quadro 2000 and a fake one (other than the fact that one works for VGA passthrough in Xen and the other does not). And while we're on the subject, on a GTS450, modding to a Q2000 does improve performance of some SPEC tests (Maya goes up by about 40%, although it is still well short of a real Q2000 score on it). On a GTX580/Q7000, there is no difference in SPEC performance whatsoever before/after the mod (in both cases the mod consisted of strap and BIOS device ID changes, nothing else). In the GTS450 case a real Q2000 BIOS made no further improvement - in fact it made the scores worse due to the lower clock speeds being set.