Which? are trying to do a collective energy switch i.e. get loads of sign ups, and then use those numbers to bargain with the big energy companies to get the lowest tariff available. Which? gets say, a million sign ups and then says 'OK big fat energy company, you get these customers if you can offer us a low enough bill'.
they have 60K+ registered interested so far, why on earth would anyone NOT sign up?
SO LET'S DO IT!