Rendering an OpenGL scene to a texture (RTT) offers many advantages to refine the look of your output, however it comes at the cost of losing hardware anti-aliasing (eg jit.window @fsaa 1 has no effect on the output).
Fortunately, there is an easy solution. Simply pass the final output texture through an FXAA shader. http://en.wikipedia.org/wiki/Fast_approximate_anti-aliasing
The patch shown below demonstrates this technique.
If you're still not satisfied with the AA, you can refine further by rendering your scene to a texture at double resolution, and downsampling using filtering before applying the FXAA.
Patches and the FXAA shader are attached.