+1, IMHO.

The one thing I know nothing about is the whatsit-thingy, otherwice you will be fine.

Tweaking it requires no flashing, except for until you get to pretty advanced stuff. And if/when you do, it is not that difficult.

On top of that, if you have willingness to learn new things, N9 will enable you to do that, for years to come, unlike Lumia 800 would.
If you are not into that kind of thing, you can just enjoy one of the very best & most beautiful mobile UI's ever created.