Strictly speaking if the system is still ultimately d20 then everything under it is cross compatible. This is what I was getting at with my post; d20 itself isn't a game, and its d20 that people are referring to when they point at things like the resolution system or skills being the same, and thus 1DND is "not" a new edition.
Which, of course, doesn't really follow unless one takes to the logic that updates to the SRD/OGL are what mark new editions. But even then, I could easily make the argument that the move to Creative Commons made such a change.
And meanwhile, the compatibility between different sets of content isn't even whats being argued by the people who assert this isn't a new edition.
Remember, the logic being used here is that because the underlying system isn't changing, its not a new edition, no matter how extensive the changes in content are. But that logic doesn't follow, and falls apart even when given the benefit of the doubt.
Ultimately, though, one also just has to consider what precisely is the hesitation towards accepting 1DND as a new edition. We know what WOTCs hesitation is, and that, if nothing else, is understandable.
I don't recall seeing anyone in this topic expressing why they don't want 1DND called a new edition, nor for that matter why itd be such an issue for them if it was.
