Although I've never used the title, I am also in the "recovering Calvinist" camp.
Unless I've overlooked it, no one in this thread has really hit the nail on the head as to what the most fundamental difference is between Orthodoxy and Calvinism, and why the two are so incompatible.
The Orthodox understanding of God as revealed in Christ is that the very core and heart of who God is is that God is love. Christ both defined and demonstrated that for us when He told us that "no greater love has any man than this, that he lay down his life for his friend." When Christ was hanging from the Tree and pouring out His life for us, He was manifesting in space and time what has been manifest for all eternity in the life of the Trinity. God is a God who humbles Himself and who eternally empties Himself for the sake of another.
The Calvinist understanding of God, as they believe is revealed in the consensus of Scripture as they understand it, is that God's highest aim is self-glorification. For them, God only does things because it brings glory to Himself. God is essentially inward-seeking and self-serving.
There lies the difference, and from that almost all other differences flow.