Besides Atny286 who posted earlier in this thread (and who also has a thread on which mods are needed to bring it to EU specs), I do not know of many people who reimported their M in the EU, but in my opinion, this is totally worth it! One of my colleagues relocated to Switzerland and him and his family brought their 328xIT with them, and registration was a piece of cake... after deletion of the the orange corner.
Of course the cost of ownership is higher there (insurance, gas, ...), but given the prices of cars in EU, who wouldn't like to ride his/her M rather than a Peugeot?? I would even rather take the bus or my bicycle during the week in order to be able to enjoy the M on weekends!!!
Also, I am sure that the dealers would be able to figure it out, especially if you approach one of your local dealers with a good attitude (and may be a good bottle of wine). I mean after all, they'd rather make (a lot?) money doing your service than none at all, even if they did not sell you the car. Worse case scenario, your wife could contact some of the German dealers who are used to servicing cars owned by US soldiers stationed in Germany in order to get the needed information. From Normandie you are also not that far away from Belgium or the Netherlands where you could find good dealers.
FYI, I am also considering relocating to the EU in the coming years/months, so let's stay in touch.
I say: don't be afraid and do it!!