The later models are far superior in my eyes, plus that font for 'ROCKBASS' on the headstock of the old models just looks cheap to be honest.
They use all the same hardware, pickups etc as German ones but the Pre-amps are different, I am never sure exactly how as they are still MEC units but they are slightly different set ups to on the German wicks.
Good basses but as always with the market how it is if you are looking at new Rockbasses get down to for sale on here, I got my Corvette for £400... for a German one second hand...
That is less than a new rockbass.