The only reason I approve of this role is because it adds a proper equivalent to godfather (miller appears as mafia on lynch but godfather doesn't appear as villager on death).
Hell, Miller is much better because it promotes scumhunting; eg checking if there's any scumreads on a lynched guilty after death. Suspect eliminates any of that in favor of more bland, easier play.
Sorry Riddler, but even in competitive play this is really bland. It's only going to be used for classic mafia setups and that's it. There's not much else to it that Miller can't do better.