The site's first tested Sigma 50mm f/1.4 DG HSM Art Lens was provided by Sigma. That Sigma could have handpicked a superior lens was questioned, so I picked up a retail copy of this lens to verify the image quality this lens model delivers.
The image quality results from the second lens are now included in the Sigma 50mm f/1.4 DG HSM Art Lens Review. The first link loads a comparison between the two lenses with the new lens shown on the left (sample "1"). I would say that the second lens is even slightly sharper than the already-impressive first lens. AF consistency for the second lens is the same as the first.
Image quality test results from the EOS 60D are also now included for this lens.