[TheVerk]

For those still wondering: Yep, it really works.

I followed the next steps (using the AI driver)
1 - upgrade FW -> 1.03
2 - upgrade IEEE1394 -> 1.07
3 - removed AI/mlan drivers/tools for n*
* tools for n probably not nessesary, I just removed all Yamaha software.
4 - Installed MR FW drivers (which support the N12) the MR tools utility identified the N12 correctly.
5 - Tested my N12: Ok
6 - Bought the MR816 CSX
7 - Connected it (N12 FW2 -> MR816 FW1), power on
8 - Installed again the MR drivers and tools for MR (somehow it
seems without the MR816 connected not everything is installed properly)
(I'm not sure if this was nessesary, the MR816 is more complex than the N12, maybe I just didn't understand it was working OK?)
10 - re-installed 'tools for n'. (unnessesary too, see 3)

And this on a windows vista home edition pc! (32 bit)
Cubase studio 4.5.2

And it works great: 16 x mic inputs total, 2 x stereo in
During mixing set the recorded tracks output -> stereo out n12 (LR)
(like normal itb mixing) but now you can use in the 'MR recorded' channels the 'morphing comp. and eq' as an insert! Works great! And you can
use the REV X reverb as an VST (so usable from all tracks: create an effect track, assign the REV X to it and make a 'send' from all tracks.

ps. Thanks George for all the work you put into this thread, succes with your new job!