Definitely less votes. I think 7, as even very hostile, 14 doesn't reach consensus. Lower votes also means that reaching consensus is harder however, the consensus reached might be better.
As for downvotes. I am not sure if it changes much, as the up votes can be moved quickly onto other witnesses anyway. I will have to think more on it.
In general, it should be made as simple and clear as possible, and having less votes helps that a lot. 30 is far too many as it is impossible to know what 30 of them stand for at any given time.