With the new update with the field scout perk moving the extra rounds to your reserve, it really strips the ThunderLord of it's exotic perk. By the time it starts firing super fast (lightning rounds) the mag is empty. Bungie should keep the field scout perk for the ThunderLord how it was pre-update.
The biggest issue is this perk carries over to the YR2 version. Seeing as Bungie have seen fit to remove this perk, it means a gun which isn't even available to us yet already has a wasted perk on it.