Well, see, we can't tell you how Maemo on the N900 compares to Symbian, because the N900 will come with a new version of Maemo that none of us have tried yet (except in a beta SDK, which isn't really the same).

#2 will always be a problem on every device, and from what I've seen, it will be a problem moving to the N900 (Maemo 5). And it sounds like there'll be another break for the next OS (Maemo 6), when they move to the QT toolkit.

But since you don't own any Maemo devices, why are you asking about compatibility issues?

#5 should be just as you want it on the N900.

Other points have been addressed above, including the fact that you're complaining to the wrong forum about Symbian...