All the cult followings (people who will end up buying CDs) is switch from voting for their choice to voting to eliminate whoever they perceive as the biggest threat to their choice...the net result wouldn't change that much.
The anti-retention vote would be more diffuse. People would have 11 contestants at first to dilute such a concentrated vote. Each week it would drop and get more problematic, but it would make it much more difficult to spoof the results. I think the ONE vote option is best but probably not economical or technically possible using phones. It could work on the internet... Except I doubt that even the internet could handle that much traffic flowing into one website... The bandwidth would be astronomic.