I had the VP-12S4 and now have a JVC RS40. It is a pretty substantial upgrade. To me, the biggest difference I appreciate is the excellent black level and native contrast of the JVC. Also the lens was so good on the Marantz that it was very easy to see pixels. No pixels seen on the JVC but image is still sharp.
JVC RS600(Calibrated with Chromapure using an iD3), Stewart Cima Neve 2.35 115" diagonal screen, Lumagen Radiance XD, Darbee Darblet, Denon AVR-X7200WA(7.6.4), M&K Speakers, 6 ported 18" subs powered by 3 inuke 6000dsps, Roku 4, Panasonic UB-900 UHD blu-Ray player, HDFury