I think it would be a good idea to set armor values to a gradient so that you could mix armor types based on various builds and styles.
As it stands, if you have one heavy armor and the rest light armor, your movement is treated as heavy. There should be some sort of scale to allow for a variety of combinations and a bit more variants in builds.
For examples, having light armor with one piece of medium would still be considered light dodge, or light armor with one piece of heavy would move you only into the medium category for dodging and climbing.
Maybe this could be determined by the weight of your total armor instead of the type of armor equipped, or it could just be amount of pieces equipped.