I doubt if you can get actual proof of 2D quality without seeing the video card AND monitor combination with your own two eyes. You can certainly gather lots of opinions, though.
That said, IMHO, I have a modded Gladiac GTS and compared it to a Radeon when I trying to replace my V5500. The modded Gladiac's 2D is at least comparable to the Radeon's and for that matter, the 3D is better than the default GTS - more saturated and sharper. With a few gamma tweaks, the GTS is very close to the Radeon's 3D. With both at default, though, the Radeon's 2D is sharper and the 3D is better saturated.