Dear Peter,
I agree with your statement that the Council of Florence put forward a number of positives with respect to the East-West unity issue!
The negatives also had to do with the political backdrop to the Council (i.e. the Turks-at-the-gates-of-Constantinople thing

).
But the way in which the Latin Catholic Church dealt with the Greeks at that Council demonstrated, as I see it, a lot of theological flexibility.
Perhaps I'm wrong (and I'm sure I'll be hearing from Eli in that case!

), but it seems that, if one were going to put forward an overall, simplistic framework for the conclusions of that council, it could involve that of leaving the Eastern traditions alone while the Greeks would accept the orthodoxy of the West's positions on the Filioque etc.
In fact, the Greeks did not ask the West to drop its theology of the Filioque at all - only the addition to the creed which was a canonical, rather than a theological, matter.
The principle on which the theology of the Filioque was approached by both sides was a consummately Patristic one: Regardless of how the Eastern and Western Fathers expressed themselves on the matter, as they were both inspired by the same Holy Spirit, their expressions on the Procession of the Holy Spirit would mean the same thing.
This is why many Greeks at the Council accepted the validity of the theology of the Filioque as being the same as what the Greek Fathers had taught.
This is also why, truth be told, St Mark of Ephesus, that great "arch-dissident"

affirmed that the "Testimonies of the Western teachers I neither recognize nor accept - I surmise they be corrupted."
In other words, when faced with the Patristic texts of the Western Fathers on the Filioque, the Archbishop of Ephesus refused to admit, on the plain face of them, that the West taught what the East had always taught about the Procession of the Holy Spirit. He not only refused to accept them, but he even made the claim that the texts of the Western Fathers had been "doctored" by the Latin theologians at the Council!
I don't see any Orthodox theologian defending that action by their St Mark of Ephesus . . . in fact, Fr. John Meyendorff didn't highly prize St Mark's theological acumen at Florence as a whole.
St Gennadios Scholarios was another story altogether, as we know, and although he was against union with Rome, as well, this didn't prevent him from highly praising the work of Aquinas etc.
The Council of Florence was also an advance over the union council of Lyons in the 13th century with respect to the Filioque.
The Greeks who came into union with Rome at that Council (including, according to Fr. Holweck, the Metropolitan of Kiev, St Peter Akerovych, himself by way of a personal union) accepted the Filioque, theologically and canonically, as Rome required at that time.
Florence required no such thing. The Latin Catholic Church affirmed the legitimacy of, albeit its own, vision of Eastern Catholic theology and canonical traditions. In short, I would be so bold as to say that what Florence represented in East-West relations in 1440 is what the current Pope of Rome has also said with respect to the same matter.
Perhaps even more importantly, Florence led to the Union of Brest in 1596. What I mean to say is that when the Ruthenian Orthodox bishops (Ukrainian and Belarusyan) sought to come out from under Constantinople (for various reasons, including some dubious ones) and achieve union with Rome (and with Western European civilization), they had a ready example of a church union document, that of the Council of Florence, that they examined and . . . could live with and that were reflected in the 33 points of agreement of Brest.
That is truly the great achievement of the Council of Florence, I believe!
The problem is that a number of EC Churches have come so far away from even the principles enunciated at the Council of Florence that if our bishops fully implemented them TODAY - many parishioners would simply feel awkward in their own parishes.
Papal Primacy and the way it was expressed at Florence would have been much less of a shock to the Greeks at the time.
Patriarchs were given to using all sorts of rather effervescent titles and claiming powers - some legitimate, as in the case of Elder Rome - and others not so legitimate.
Alexandria is a case in point. It claimed to be second in command after Rome because it was founded by St Peter's assistant, St Mark the Evangelist i.e. the "Evangelical See."
It was Alexandria, not Rome, that FIRST claimed immediate, universal (ecumenical) jurisdiction over EVERY church and priest in Christian Africa at the time. That wasn't even on Rome's radar screen as yet, and the Pope of Rome was earlier referred to as "His Beatitude" and "Bishop of Rome" with "pope" the invention of Alexandria.
Papal jurisdiction of this sort which was later affirmed by the Pope of Rome is, therefore, (dare I say it? Will you come to my rescue?

) a product of Eastern Christian ecclesiology in the first instance . . .
The Greeks of Constantinople had a history of a long struggle with Alexandria over these same claims and, in the course of them, preferred to have Elder Rome exercise those prerogatives rather than Alexandria - something that Alexandria never forgave Constantinople "the usurper for second place" for.
The Greeks already had a history of "hands on" experience with papal jurisdiction - during their political fights between Emperor and Patriarch. Rome was their convenient - and necessary - referree.
Let's also remember that it was Constantinople - not Rome - that gave Rome the many superlatives with respect to St Peter's prerogatives etc. at the Sixth Ecumenical Council.
As for the Filioque, Fr. Meyendorff sometimes mentioned the fact that there were times when the Greek theologians did not protest against its inclusion in the creed - depending on the state of relations between Rome and Constantinople of the day.
EC's sometimes have the lamentable habit (and I'm an EC too!

) of comparing their own often Latinized state today to that of past Councils like Florence.
Florence did not "Latinize" anyone - we EC's did that to ourselves via our bishops and others.
Florence laid out an ideal, which would have been different, of course, if Florence were held today.
If we EC's could begin to live that Florentine ideal today in our eccesial praxis, we will have returned to a great deal of our genuine ecclesial traditions.
Alex