We never did full-on EC, but since 6 months old ds would go on the potty at least half the time. At around 13 months he would sit himself on the potty every morning to poop.
I didn't notice that it was waning at first. But now (along with his "NO" answers to everything else), he refuses the potty completely. Anytime I try to sit him on it or hold him over I get The Dreaded Back Arch.
For the time being I don't try to take him at all, though I will point out the potty and leave it out for him. He'll sit on it for fun but then go in his dipe, or even nearby on the floor if he is bare.
I am figuring I just need to wait it out. I am still hopeful that the control he learned from ec will help him get into udies during his 2nd year. But I'd love to hear some BTDT stories.