Could still be cheated by the autovoters ( like the one we mentioned, i bet they have such things ). Setting up an auto clicker script on your server, setting up the window px dimensions where the captcha is located and programming the clicker to move the captcha so its unlocked.
Such things might work a few weeks, but i saw the inside of the mentioned cheat program and they seem to release new ways to crack security as soon as things not work anymore
I fear in the end, and with always advancing technologies it will be harder to counter such programs.
Questions is, how many of your members use it? Is it worth spending repeated 100's hours of fighting back just 1 program? When one can deactivate suspected members.
If one not want registrations in order to vote, there will always come some new guys