I use MM rattle-can buffing metalizers quite a bit and like them very well. Their biggest problem is that the finish is very soft. It doesn't mask well at all, and it wubs off easily. I usually spray a coat of Future over it, and while this does knock down the sheen slightly (not much, but slightly) it eliminates the problems of rubbing off and it can be lightly masked.
I recently tried Alclad for the first time, and while it looks fine the paint is very thin and I had problems getting it to cover properly.