While considering the whole Improved Familiar plus Morphic Familiar paradigm, a thought popped into my head:
What happens if a Changeling wizard with Morphic Familiar goes into Arcane Hierophant?
Now, this isn't likely to happen often, since he'd have to go to level 5 as a wizard, which is not particularly optimal for AH. But if he did...what would be the outcome?
It seems like it all hinges on whether your Companion Familiar is or is not a familiar, which is debatable by the wording of the ability.
If it DOES count as a familiar, then by the wording of Morphic Familiar, it could assume the form of any creature the character could have as a familiar--which, in this case, would be any animal companion of appropriate level. Essentially, Wildshape for a familiar.
If it DOESN'T count as a familiar, but instead as an animal companion with some familiar abilities, then the wizard's just hosed.