But in many ways there is a far greater difference with Gandalf, then the fact that he was in grey during the fellowship and white afterwards.
In the case of Pippin, its still Pippin, in that he was a member of the fellowship and hence you still have him, even tho he is wearing Gondorian armour.
That, however, I think is fair to say, is not a fellowship piece, in so much as he doesn't look like he did, when the fellowship was all together at the start.
So all I'm saying is that a distinction can be made between wanting the Fellowship members, compared to wanting them all as 'fellowship pieces'. If you all really want 'fellowship pieces', then I think Dio's is likely your best chance, but even then not very likely.
As for the PF's and Aragorn, yes, you'd have to remove the Elven cloak and funny enough, not get the EX, since I'm pretty sure he didn't have that knife to start with.
So the only true fellowship PF so far, has been Frodo