Well, not to push you one way or another, but here's a couple thoughts to add to your list. (FWIW I have an N800 and am still waiting for my N810 to ship, sigh)

The N810 has a brigher screen (20% reported, whatever that means) and has much better viewing in direct sunlight (as reported by serveral people).

I wouldn't really give much weight to the swivel camera though, if your purpose is photos. Neither unit has that great of a camera for still shots. (think cheap/free cell phone quality). However I have used the swivel ocasionally on video calls to wife. (IMO video quality isn't that bad over SIP directly, Gizmo's implementation is a little raw looking) So it can be handy.

Like you, I wasn't placing much weight on the GPS. I certainly don't need it to drive around rural Montana where I live. However, Maemo mapper with Google sat maps will be another story. Camping, hiking, fishing, skiing backcountry, etc... I'm actually looking forward to it now.

On the other hand, the N800 is really a bargain now and runs the same OS, same speed, etc. That's why I just can't see getting rid of mine, even when the new one comes. I know it will be useful for quite a while still.

You really can't go wrong with either IMO.