Panasonic 12-35mm Ephotozine vs SLRGear

It would be nice to have a source of objective evaluations of the basic elements of lens quality. I have looked to SLRGear and Ephotozine among others for such evaluations but they frequently disagree. In the case of Panasonic's 12-35mm x zoom, SLRGear has the lens producing tack sharp performance across the zoom range at f4 while Ephotozine has the it producing results inferior to the old Panasonic 14-45mm. True, SLRGear is testing a pre-production copy of the lens. But, if that is the source of the difference, SLRGear is wasting their time and ours testing pre-production copies. Perhaps the tolerances maintained in lens production are so loose that testing any single copy of a lens except the one you are considering purchasing is virtually meaningless. If that's the case, I guess we're just going to have to buy and try and send back the ones that don't meet our requirements.