You Know Who You Are....
For many conservative Catholics, the Papacy is about signing the dotted-line but disregarding the fine print. They use Patristic sources to paint a broad picture about how things should be, but never get into specifics on how it all works. Are there Papal maximalist texts in the writings of the early Church? Yes. Does that mean that this enables Papal power to change the formulation of doctrine, liturgy, or to even choose bishops half-way around the world? No.
Romans were a very legal people. The Catholic Church is a very legal Church. So let's cut to the chase and talk about the fine print of the deal. How much power would the Pope have if the Orthodox Church came under him? How much could he intervene? Would he have to sign something saying that he could do ABC and not XYZ? If the Orthdox or continuing Anglicans ever do get an acceptable union deal from Rome, I would advise them to get a pre-nup.
Many Catholics would protest that of course Papal power is limited by Tradition, Scripture, etc., but the Vatican can always muster up spin doctors to justify anything (they're called Jesuits). So we have either two options: we can either return to the traditional ethos of the Church as obedience to Scripture and Tradition whether we like it or not, or we can elaborate our ecclesiastical legal system some more so no one gets hurt. Otherwise, we will just have the anarchy of going from one Pontiff to another who wants to re-invent the wheel at the beginning of his reign.