Waaay late to the party but here goes: on RFF 'the Master of Sonnar' Brian Sweeney posted that the black Jupiters in general are more sloppy in their optics than the earlier chrome lenses. As said above, get the Jupiter-8 and Jupiter-3 with as early a serial number as possible (first two digits show year built).
Brian shims them to match Leica standards, to which the Bessas are also built. Without getting too technical, when shimming and thus optimizing for close up and wide open, the increasing DOF when focusing farther away will cover the focus error and as a result you can have a lens that is spot-on both near and far. The whole optics module just threads out with aperture and all, it does on Jupiters -3, -8, -9 and possibly -11.
Remember, SLOBB = Silver Lens On Black Body = cool. It just oozes professionalism