I doubt very much that the lens used in the new RSs is one that was specially developed for JVC. Even the what are considered excellent quality Marantz lenses are off the shelf lenses.
I understand this to be true because lens development costs are extremely high. Thus, the cost of developing one for a specific projector would never be recouped in the low volume projector business (unless the projectors cost an arm and a leg).
It is likely that JVC shopped around for an off the shelf lens that met its needs. Perhaps they even have the manufacturer tweak it a little.
I am still skeptical that a new lens will have a very dramatic effect, at least on sharpness, if you have a good RS1/RS2. Now whether the new optical path and lens increases MTF, that is something else altogether.
On another note, I wonder what it is about the new design of the RSs that saves costs over the old one?