In the past i have made longer test, but the result was alway similar.
Your are faster with lighter armour, but the effect is minimal.
On a longer track you can beat a plate user about a couple of seconds, but in battle you have a way shorter ways (that is why i have used side steps this time).
I dont ask for gimping heavy armour, it should provide more potection than the lighter counterparts, while offer mobility as well, but i think the payoff could be a bit larger.
Ok, a few rough numbers for my example.
For 1/4 of the weight and 1/3 of the protection i get a 1/5 faster movement.