Well, practice is, perhaps, more relevant than mere theory. I have not used such an enlarger but I am still afraid to as I am immaculate when it comes to dust. True, the enlarger (Focomat) would not have been so prominent (in a previous age) unless it delivered. But I still do not want one. The slight advantage of having the top of the negative flatter is 'undone' when you stop down the lens. Just a thought here. - David Lyga