Well I don't want to discourage you too much, but this kind of discussion has come up many times in the past, and each time it has been shot down by one or more of the fractured Amiga groups for multiple reasons, so I would not get your hopes up too high, until you see some agreement and cooperation from the developers in control of each separate group. I was one of the naive people that put out a call for unification, or at least cooperation in the past, so I applaud your sentiment and efforts and hope that it is received better now than it has been in the past.
There are some differences this time, indeed. First of all, Amiga25 is not about unification, but about common features. Amiga25 role is not trying to unificate the whole Amiga community if it doesn't want to, nor to create any 'new everybody's OS', but only encouraging coders to write software that can be useful for ALL the 'amiga flavours' available today. Just think at something like NoWinEd or WookieChat, which are available for every Amigaish operating systems out there. Encouraging, in the plans, means money.
