Reading your post, and if I were you, I would get the Droid and maybe pick up a small tablet running Linux. I got the SmartV7 and am enjoying it a lot for about $200 - there are other, better options out.

The N900 is to me very much an interim stepping stone with flaws that will never bed worked out due to the short lifespan it will have.

The next N will have significant changes to both screen type and operating system (Harmattan) to just mention two known ones.The maemo development community also need to grow before it moves away from the 'beta-then-discontinued'-state that so many Diablo apps exist(ed) in.

The droid development community does seem active and as many have expressed on this forum: You don't/shouldn't have access to the command line as a user - then there is no big difference between using the two.

End of the day either device is a phone with some bells and whistles. Pick the ones that works for you. Neither is a laptop replacement.