Basically, my position is the same as that of then-Cardinal Ratzinger, which is presumably also his position as pope. (The relevant texts appear in the Pontifications combox.) Thus, that "ecclesiology of communion" which was more or less held in common by East and West in the first millennium is compatible with the doctrine of papal authority developed since by the Catholic Church. The position taken by the Orthodox, predictably enough, is that the two are incompatible. While I don't always follow the logic of their objections, the idea seems to be that the college of bishops, which comprises equals who are "vicars" of Christ, cannot constitute a body of equals united in love if one among them, as their head, can overrule or issue orders to the rest taken either collectively or individually. Thus on the Catholic account of episcopal collegiality, the college of bishops is not a true communion or koinonia as commonly understood in the first millennium. And so Vatican I's dogma of supreme papal jurisdiction is not a legitimate development of doctrine.
Let me say right off that there's no point in debating history here. Each side takes the same set of data and interprets it from within their respective ecclesiological frameworks. The central disagreement is not about what was once said or even about what actually happened back then. The central disagreement is about what the Holy Spirit meant by what was said and done back then. While that disagreement won't be settled here, or indeed anywhere anytime soon, one thing that can and should be shown is that there is no conceptual difficulty about combining authority and koinonia among equals.
For instance, in Ephesians 5, St. Paul treats wives and husbands as equals—"submit to one another"—but also says that wives must submit to husbands as "to Christ," who is Head of the Church. Thus the husband is "head" of the wife. That clearly does not mean that the husband is master and the wife slave; as rational adults, they are equals. But traditionally, it has been taken to mean that the husband has the last word when major decisions are to be made. And that has always made sense to me. In a community of two, dissensus cannot be resolved by majority vote; at the end of the day, somebody has to decide and the other has to accept that decision. Of course, nowadays, the idea that the one deciding should presumptively be the husband is quite unpopular. When they give the matter serious thought, most people say that all decisions should be joint or, failing that, that the last word should be with the wisest or most competent decision-maker—which, one must admit, is often enough the wife. Some would even say that, while men may "reign" in the home, it's pretty much always been wives who "rule." (Thus Einstein once said: "When we married, it was agreed that I would make the major decisions and my wife would make the minor ones. So far, there have been no major decisions to make.") But regardless, the very idea that one should decide and the other submit is unpopular. And I believe that's been undeniably to our cultural detriment. It goes against both traditional good sense and the nature of Christian marriage as a sacrament of Christ's relationship with the Church.
Even so, it's crucial to remember that male headship in marriage, when understood and lived as it's meant to be, is one of service not domination. With all such authority, in whatever walk of life, comes the responsibility to sacrifice oneself fully for the one(s) under authority, just as Christ did for us on the Cross. Similarly, one might say that the koinonia of the college of bishops is not crushed but rather facilitated by its having a head who sees his authority as service not domination. His supreme jurisdiction, while real, is abused if imposed arbitrarily and/or without consultation and respect. Thus papal authority as defined at Vatican I, and described further by Vatican II in relation to that of the bishops, is compatible with the ancient ecclesiology of communion. Such authority, when properly exercised, is a cross not a license.
That won't satisfy most Orthodox, of course. No refinements and qualifications such as I've outlined above will silence the objection that, whatever the papacy ought to do, the mere fact of what Vatican I says it can do is incompatible with episcopal koinonia. While I don't buy that objection, the Catholic Church needs to do more to meet it. Perhaps she could start by applying the principle of subsidiarity, so admirably developed by the social teaching of recent popes, to ecclesiology.