Every dancer (or dance) Should provide you a different stat boost, just like potions do. A certain dance increases your STR, another gives you more AGI, and so on.
This makes so having your house full of entertainers a desirable thing, since your chances of survival increase as your stats are boosted (it would ideally only increase stats of their owner/guildmates)
Higher tier thralls would give higher values for each stat. A T4 thrall should be stronger than fish buffs, or potions.
They should not stack with potions, and that seems fairly simple to deal with. Once you have a Strenght dancer around, you get the Str buff, and it can’t be overlapped by another potion or fish.
Does that sound reasonable?