1) I have a perfectly functional 800
2) The price is high to me (though I can understand cause if I had to pay for a new GPS unit and cell phone to tether and the extra SD cards it would reach into the realm of the 900 (since I paid full retail when I purchased the 800)
3) I am concerned about this reboot issue. Had it on my 800 and when the thing is also my phone that is not going to be cool.
4) I'm using SD boot. Not sure if this is something that can/should be done on the 900.
5) MaemoMapper: Absolutely must work on the new device or some equivalent as I use my 800 as my only navigation device on long road trips.
6) I recently purchased the Mugen battery for my 800 and I'd like to actually use it before relegating the 800 to the relic closet.

7) Lastly I'm on ATT so I lose 3G not the biggest deal but I'd like an idea on how web surfing is like on GPRS speeds, 3G over a tether is well sluggish but usable for MM updates.