I disagree that the mafia don't really need investigations in this format.
They only get 1 hit which I think is to low.
A PR isn't just a PR, in this game. They would probably prefer to kill off a Psychic over an Exorcist in this game.
I skimmed so this might be moot. Since the evils get 1 hit, if they use it and get say the Exorcist.what is to prevent the Dr/Psychic from coming out? Multiple hits available usually keep this in check.
As for witness, it depends on how you decide who sees and what they see. Whats the info they get? Only having 1 hit makes the game really hard for mafia teams.They are already disadvantaged only having 1 hit, why rat them out?