I have been running a rig shooter Palana deck lately. It uses Marcus to take out their rig. Ark Lockdown to keep the rig gone. Caprice to allow you to score out or Siphon protection. Friends in High Places to recur Marcus and Caprice. As you could guess, the deck really struggles against Rumor Mill.
In saying that, you would be surprised with how many decks are not running Rumor Mill. Even the anarchs I play, most of them do not play it or do not find it. Hopefully by the time they have found it, you have rushed out a Nisei and can stop them getting into the remote twice. You can then play your own current and try to score out the next Nisei. Val with Blackmail + Rumor Mill can easily be an auto-lose.
Yes, competitively it is a gamble (but I am playing Psi games for my win condition so I'm already gambling). The way I see it, you can either play a corp deck which can get you a 50% winrate against 100% of the field or a corp deck that most people are not ready for and wins more often than not against decks that do not run Rumor Mill.