Under the doctrinally pluralistic realm of modern Roman Catholicism, it makes no sense for a group to forgo "full Communion with Rome" on doctrinal grounds because one can submit to the pope without actually believing what he believes, apparently.
but what if the Pope decided to go ex cathedra and proclaim something which is contrary to the Ecumenical Councils and Christian Doctrine and does so by asserting his Papal Infallibility?
Under Catholic doctrine, you have to believe what the Pope would say if something like this occurs like it or not. After all if a Catholic doesn't, he/she is going against the decree of the Holy Spirit as it is He/it(I dunno whether it is appropriate to refer to the Holy Spirit as "He") moved the Pope to make such a pronunciation as Catholic doctrine teaches.
The New York Time's conservative columnist, a Roman Catholic, Russ Douthout addressed this Sunday in his column in terms that are rather understandable to the Orthodox mind and which put an 'interesting' spin on these isses of infallibility. http://nytimes.com/2014/10/26/opinion/sunday/ross-douthat-the-pope-and-the-precipice.html
This article is very clear about where infallibility stands in relation to Holy Tradition in Douthout's mind, a teaching which Mardukum has mentioned and repeated consistently on this and other fora.
From the article:
"Francis is charismatic, popular, widely beloved. He has, until this point, faced strong criticism only from the church’s traditionalist fringe, and managed to unite most Catholics in admiration for his ministry. There are ways that he can shape the church without calling doctrine into question, and avenues he can explore (annulment reform, in particular) that would bring more people back to the sacraments without a crisis. He can be, as he clearly wishes to be, a progressive pope, a pope of social justice — and he does not have to break the church to do it.
But if he seems to be choosing the more dangerous path — if he moves to reassign potential critics in the hierarchy, if he seems to be stacking the next synod’s ranks with supporters of a sweeping change — then conservative Catholics will need a cleareyed understanding of the situation.
They can certainly persist in the belief that God protects the church from self-contradiction. But they might want to consider the possibility that they have a role to play, and that this pope may be preserved from error only if the church itself resists him."