Raid sets are comming soon, you can define exactly who you want in each group, name of the group and how many groups you want - should solve the shaman/paladin problem, but will be a lot more advanced :|
Filter Sets => Set: By Role => Frame #1 (Tanks) => Groups =>
After I clicked a group, I was not able to unselect this group from this role.
And I have another suggestion, perhaps make it possible for people to choose which buff they want to see. For instance, showing only Soulstones, or showing only Fortitude.
It's looking great by the way, thanks for your effort.