Of all of the problems that Panda has, this should be the very last reason for not using P3D. Like I said, if you have a simple setup, use the default MSAA. It is fast enough if you don’t do any post processing in opengl or offscreen buffers in Dx9.
If you have a complex setup, you will want to use shader based FXAA or MLAA anyway … unless you think you can do better than Battlefield 3, Cry Engine … which ALL are moving to shader based AA solutions. I can’t think of a reason why you wouldn’t want to use shader AA as they run 5-6x faster than regular MSAA.