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.
Maybe try teaching him to go standing up? It might help switch things up for him to regain some interest. It also helps make it an easier and quicker process. There are little boy urinals out there (http://www.amazon.com/WeeMan-Potty-Training-Urinal-Product/dp/B002RZ1Q54/ref=pd_sim_sbs_ba_2). We used this one at first (later my sister sent me one from Korea that has suction cups so it doesnt' need to be attached to the toilet which was a hygienic leap in the right direction - I can't find them out here though). My DS really likes going standing up because it is 'like Daddy' and he does not need to have his pants all the way off to do it. Similarly, if he is really absorbed in doing something, I can just bring a jar over to where he is, pull his pants down without disturbing him, and let him go in that (sometimes without even saying anything, he just goes when it is in place).
The other thing that seemed to help when we were having some backlash was just to say 'hey, its been a while since you went pee'. He would usually say he didn't need to go, but then would announce a few minutes later that he did need to and we would both yell 'woa woa woa' and run to the bathroom together, which he seemed to enjoy.
It also seemed to be that when he got really resistant, I was offering or suggesting too often because he had progressed to a new stage of bladder capacity or holding ability or something. So if I totally backed off and adjusted my timing, he was less annoyed by my overly-frequent offerings and we would get back on track. Best of luck! This was the hardest part for me by far.