I use lights. The top on my dread is lightly built and it doesnt need mediums. I think it really depends on the guitar. Some dreads sound best with meds, some with lights.
Only one way to find out.
I will say I picked out a MMV for a friend a couple years back. It was a great sounding guitar. If I wasnt helping him pick out a guitar I would have bought it for myself. It sounded just as good as guitars priced two to three times as much to my ear.
I still ask him about once a month if he wants to sell it to me.