I dont think he advises against a common super but said it is not good if you remove the super and you then have to feed the nucs.
Aaah, now that you put it like that, it makes more sense. I misunderstood what he said, then: I thought he meant that it is not good to have a common super, because it would mean that you would have to feed like crazy, but your interpretation makes more sense: i.e. he meant you have to feed like crazy AFTER you've removed the super (instead of before you remove it).
So if you don't remove the super (i.e. if you don't use the super for honey harvesting but simply as stores in aid of brood building), then it would no longer be such a bad idea to use a common super, right? Although, if you don't remove the super, you'd still have to remove the queen excluder before winter, and you'd have to add a vertical queen excluder in the super. Come to think of it, wouldn't it be best to simply use a vertical queen excluder in the super anyway, instead of a horizontal one?
It is also possible that I misunderstood what is meant by "super" (meant by him and meant by his audience). To my mind, the term "super" simply refers to a hive box that you put on top of the other boxes, which usually gets filled with honey (regardless of whether the honey is intended for harvest or for colony growth), but perhaps he/his audience use the word "super" to mean specifically a box that is intended for honey harvest.
If that is so, then it makes even more sense why he calls this a "bad idea" because his nuc method is not intended for increasing honey harvest but to increase the number of viable colonies that can be used as honey harvest colonies... later. Am I right?
I dont know what you are referring to regarding the floor...
Well, I'm willing to learn what you mean by it, but I would have thought that "integral/integrated floor" means that the underside of the nuc box is fixed to the box and can't be removed. Many nuc boxes are made like that, because they are intended as temporary dwellings for small colonies of bees. One would not be able to use a nuc box with "integrated floor" for Mike's method unless you break off the floor (assuming you can), make a hole in the floor, or lead a flexible hose from the nuc to the box underneath it.