What counts as a slight disadvantage/normal disadvantage can change from person to person, just like a bigger number scale. However, due to less options to choose from, it's even more vague as to what the board feels is a harder MU compared to another one.
It's not as precise, and leaves more room for confusion, not less. #5-#5 system is the best way to go when it comes to being precise, but not being ridiculously precise. All they had to do was give general terms to each step in the scale. Instead, they went for a smaller, very broad term scale without explaining what counts as a "slight disadvantage" or "normal disadvantage". That, and it oh so conveniently leaves MK with three neutral MUs when we all know he doesn't actually have any truly neutral MUs. Good job covering your tracks so you can avoid more MK ban discussions in the future by saying "but he has neutral MUs!".
The new system is just causing more problems then it's "fixing", and I see no reason to use it at all.