Nikon vs Sigma 24-70mm f/2.8 lens comparison?

Nikon AF-S 24-70mm f/2.8G ED N Lens
vs
Sigma 24-70mm f/2.8 IF EX DG HSM Lens-Nikon

Has anyone tested these two lenses against each other?

Sort of… Photozone.

http://www.photozone.de/..._28_hsm_dx

http://www.photozone.de/...est-report

Tested on the same camera, and you can compare the results and look at sample images.