(Llorean: as there doesn't seem to be a 'correct' place to ask this kind of question I'll answer it here anyway. It's a question I knew would crop up eventually...)
The D2 I use for development is a DAB model, so yes, if and when a Rockbox port is made available it should run on your player (it also shouldn't matter whether you have a 2, 4, or 8Gb model). There will be no DAB support, at least to begin with, but you will be able to dual-boot to the Cowon firmware if you want to listen to DAB.
In the meantime, until the D2 is a supported target, it is probably best to ask any general questions over in the Rockbox thread at iAudiophile.net.