Well, you just pick the device you think is best for you the moment you buy it...
Right now as far as functional but still open goes, the only real choice is Maemo...
we'll see how that evolves... I thought nokia was all about having 9999 niche market?

Also portability will not be as much of an issue with the QT compatibility in Maemo6.

EDIT: also looking at the entire pdf (just search maemo over and over) you'll see what they have in store...