Matters on usage. I'm eyeballing a Lumia 900 because I can get it cheaper than I did a N9 and will have a Google Voice app that works like I need it to - GoVoice on WP7 isn't half bad actually. And I'm REALLY missing voice commands.

But let's be honest. You want the N9 because it's different, it has terminal, you like to tinker a bit, you like USB mass storage and you more than likely will regret going to WP7 because it will box you into that ecosystem.

Get the N9. Don't body swap this one