The thing about the heat ventilation and a 7950 GTX overheating on a M9700 is doubtful because the design of the cooling system on the M9750 and M9700 are identical, minus a few structural differences in relation to the chassis. If anything, I think the only thing limiting a 7950 GTX from working properly on a M9700 would be the power supply: the PSU for the M9750 supplies more power than that of the M9700, and both are interchangeable (I bought a broken M9700 and tried it). It shouldn't be a big issue with single card solutions, but it would be if one plans to use 2 7950 GTXs in the M9700 chassis.
I also pre-ordered an OCZ Whitebook a.k.a the Arima/Flextronics W840 Di, which is basically the 2nd generation of the M9700/M9750 chassis. It comes with the ATi Mobility Radeon 3870 in crossfire on the Montevina platform. One of the things I'll do once I get my hands on it is to see if one of the Radeon cards will work on an M9750 (I can't test on the M9700 because it's broken). I've done something mildly similar before; I took out the 7900 GS from the broken M9700 and put it in the M9750 and it booted with no issues. I wish the M9700 wasn't broken because I wanted to see the other way around. But if that's any indication of a possibility of upgradeability, then it's a positive sign.
Side note: Interesting to know that 2 Mobility 3870s in Crossfire + X9100 processor with a BIOS overclock scores at the high 14k range in 3dmark06 (NOT 05). KillerNotebooks got 15,100+ 3dmarks with their setup. A single Mobility 3870 scores around 8200-9000 3dmarks (3dmark06).