What the Orthodox have to say on this is quite Catholic, and, I trust, vice versa, what the Catholics say is Orthodox. It is after all the same unified Church that worked out the Canon.
I am not aware of anything dogmatic regarding the relative importance of the New Testament books. The idea one often hears from the Protestants, that the Epistles are what teaches doctrine, and the Gospels are of lesser doctrinal value, sounds horrifyingly foreign to me. If anything, the words of Christ to us override any other statements that might sound more systematic and theological. Of course, we don’t contemplate any internal contradiction throughout both Old (complete) and New Canons, so it is a matter of one passage read in the light of another, rather than one passage negating another. Whatever difficulties of interpretation exist, they are more pronounced between the Old and the New Testament, rather than inside the New Testament, and comparing the two it is definitely the New Testament driving the proper understanding of the Old Testament and not the other way around.
“The Church” to me and to most Catholics is the set of Catholic and Orthodox Churches that retain the apostolic succession and have valid sacraments. Since our unity is imperfect, at times, when aspects that divide us are discussed, I would use “The Church” meaning narrowly the Catholic Church united to the bishop of Rome, but not in a discussion like this one. The Catholic ecclesiology is that each regional Church under a given bishop is in herself a complete Church, even though a larger body such as the Roman Catholic Church is also a Church, consisting of many Rites, Churches, and episcopacies. This allows for a certain flexibility of terminology.
I've only been a Baptist for 35+ years, but I've never heard that. I'd gladly jump down the throat of any Protestant who uttered such nonsense. If theology is the Study of God, then what could be more valuable than the Gospels?
That said, 400+ years after the Reformation, there are many Protestant 'churches' that God hates. I thought Martin Luther's introduction to his commentary on Romans, which I read for the first time about a month ago, a GREAT summary of the Gospel. That has made the recent news of a 'Lutheran" church ordaining homosexuals all the more painful - a bitter reminder of what can happen when the tares outnumber the wheat.
I would like to be able to visit them, and utter just one sentence in front of them:
It is as impossible to separate works from faith as burning and shining from fire. - Martin Luther