Ninja Tabi Rework Idea

My friend suggested an idea towards changing Ninja Tabi: A move-speed scaling off of armor. I have not given any idea as to what the scaling would be yet but would like to hear thoughts on the concept.

Personally, I think it'd be great for gap closing on some clunkier tanks. It might also be strong on some tanks initially (e.g. Nasus) but those characters could get slight nerfs (Nasus slow/E reduced slow). It will also be useless on mages and adc, as they wont be building enough armor for it to be of value.