The supplied drivers very well might work for most but in the event they do not there needed to be a work around. Using XRender is definitely not an ideal solution because full screen flash will not work and neither will OpenGL screen savers. More that likely anything using OpenGL is not going to work using XRender, including games. I read through a lot of posts about KDE 4.6.0 and graphics problems and solutions before deciding to use the newer drivers on the xswat ppa repos.The resolution of using the XSWAT PPA may be good for the 1% of users, but for 99.9999999999999999999% of nVidia users, this is going to be an issue, and in the "minty philosophy" I think that any action that will install nVidia drivers should use these drivers since using the OEM ones will cause problems.
I tried every solution I could find before using the xswat ppa and certainly suggest that others do the same first but there are going to be people with graphics issues that need to be addressed. Mint always ships with the supported drivers for the given release but repos like the xswat ppa are there for good reason and are considered reasonably safe. xorg-edgers on the other hand use cutting edge drivers that you use at your own risk. In the end all I tried to do is provide some degree of help for someone having un-resolvable issues.
Edit: I asked when the RC might hit the public mirrors, might be waiting on testing to be completed on the x64 version.