woody, I'll just pitch in with what I know of historical facts and not really to join whatever fight is here. Some of this is more along lines of what was experienced and not really documented, but here goes:

MeeGo's base was Moblin 2.0, severely modified architectually to become MeeGo. Moblin 2.0 was built for Atom, yes. During this big modification time (what led to 1.0), the ARM port was done by both the hardware adaptation team that currently does MeeGo CE and some Linux Foundation contractors.

This practically meant, build all the source packages with ARM compiler and set up a target. Nowadays the ports are pretty equal. Initially the port was built for ARMv5 instruction set, then changed to build for ARMv7-A instruction set as this is where the most devices are based on nowadays.

Now, this portable core doesn't include hardware adaptations - like, adding in graphics drivers and other specific things, so they had to be made. Which is why we have seen the MeeGo core and UX'es on different ARMv7 devices - the core isn't specifically made for a certain device

It does actually work. The problem was that the stupid aegis security system blocked people being able to flash custom kernels in the firmware revision given out to N950 developer program people. This is fixed in a later version that N950 developer program will hopefully soon get, and N9 owners will have in sales release.

The process of this hardware adaptation for N950/N9 was similar to that of N900 - take the hardware agnostic MeeGo core, add in hardware adaptation such as GLESv2 drivers (actually shared with N900), kernel, wifi firmware/bt fimware, etc.

Just a minor comment - you state that a dialer for one device using ofono won't work on the other - that's not really true. The MeeGo dialer was made by a person from Intel who has no N900, developing it on Intel hardware + Infineon modems and we were able to use it directly on N900 + ISI modems, using same Ofono API with no source modifications.