On the subject of dewalt vs fatmax, I think there are several subtle differences, but more between batches of the same item than fatmax vs dewalt, they main being whether or not the catches have metal pins as apposed to the weaker plastic pins. I wouldn't assume the same quality across the board on one product (which is rubbish lets face it), when I looked at the fatmax tower in store in toolstation the build quility seemed good, and I'm pretty sure they had the metal pins.
I notice with the 'fatmax deep pro' organisers (as opposed to the incompatable but virtually identical 'fatmax pro stack' organisers) you get some with a waterproof seal, some without, some with metal catches, some without, some with metal pins in the side catches, some without, and reading various user reviews it seems like a lot of people think they are buying one thing and get another.
worth checking in store