The very worst thing you can do as his parents is make any kind of big deal about this in any way shape or form, by putting him back in diapers is sending him mixed messages, you are telling him that pooping is for babies and then putting him in a nappy. put him back into pants and ignore, "yes ignore altogether" when he poops in his pantys. he will soon see it does not phase you at all. do not even talk to him as you change them, that way he gets no reinforcement whatsoever be it either positive or negative, but be vigilant, yes you may have to wash pants all the time (you could buy cheap ones that you can throw away when he soils them) don't give up and try to tell your wife not to freak out at him for it, its negative reinforcement! "ignore ignore" and don't talk about poop! talk to him about anything at all afterwards "when you've changed him" (calmly) its all about praise the wanted behaviour and ignore the unwanted, i think it will work, good luck!

I thank you all for your words. I am going to read up and think more on this. But the catch to your suggestion, Debs, is that I am not home during the day with him, my wife is. I tend to be more easygoing on this, and telling someone to take it easy usually has the opposite effect, you know.