This is the solution I use as well. But there is a problem with it I haven't found a solution to. By using the option to ignore the tv as a display device, it disables the tv output on the card instead of ignoring it. When I then switch to a virtual terminal or exit from X, it does not re-enable the tv ouput. So i can no longer get a console display on my tv.
Now this would not normally be a problem, but I use my tv out for playing movies, and as a workaround want to use mplayer's ability to display to the framebuffer. But that does no good if the driver, instead of actually ignoring the display device, disables it.