I went back to butter a few years back after a dietitian at work told us the oils in the margarine are the least healthy thing to use for cooking. I also find foods taste different if you use butter over margarine even my husband noticed the difference.
I think the red container of Becel actually has it marked on it in very fine font not to use it for cooking or baking. When I tried to use it in the frying pan it melted and formed into this hard brown sticky mess and I couldn't figure out what was wrong with it. It was when I was reading all the ingredients that I found the warning not to cook with it.