Thanks guys for the responses. I agree with you both that having every possible buff on the grots will prove diminished returns.
I like the idea of having a loon boss for MWs on rolls of 6 for the unit. Add then having sporesplatters doubling the amount of attacks.
The next thing I would consider is adding yet another attack to the entire unit with using sneaky snufflers. That might be the point of overbuffing / diminishing returns?
Not to mention spiker for rerolls wounds of 1.