I would said, keep your N900 since your existing N900 already can do all what your mentioned on "1" and "2" works best on N900.. of course "3" (ls still lacking),

Regardless Samsung Galaxy or Desire...it is the same for all Android phones, They are all the same ....it is just changing the skins (UI) and add and minus some function here and there and they called it a new Android phone. Just look at there a so many Android phones out there, they all looks and function almost identical. Things u can get from one Android compare to another android are almost same. LOL.

You should wait a bit longer.... unless u have the $$$$

Good Luck