Maybe if you can get their attention. Offering a signup fee and bonus specifically aimed at that group would likely generate more interest than what they may perceive as "yet another 100+% pool". If they were paying attention, they wouldnt be mining at those pools, so the trick will be to reach them somehow.
Moreover, someone mining at deepbit may be turned down after 1 day of mining at p2pool after receiving nothing or only a fraction of that they are used to. If you can convince them to mine a week or so, then they might actually see for themselves.
Good call :/