Just received my post-CEDIA special DLA-RS4910 projector from AVS, as a replacement for my DLA-RS1 projector that's been hanging in my dedicated home theater for many years. I've been so satisfied with the RS1 performance (especially after adding a Darblet) that I haven't been compelled to upgrade for many years. Despite the coming of 4K, I finally succumbed to purchasing a new JVC projector, mostly to see if a dynamic iris and 3D would make much difference.
Our dedicated home theater has 100% light control, dark fabric-covered walls, and black velvet surrounding the screen wall -- so it's easy to appreciate the black levels of JVC projectors on my acoustically-transparent zero-gain SMX woven screen.
The bottom line: the RS4910 provides a better picture than the RS1, but it's not a huge difference unless you know what differences to look for. In fact, I imagine most people wouldn't notice that I swapped projectors. Maybe I just had a really good RS1 unit.
The e-shift 4K feature seems to be of minimal value. I can easily see when it's turned ON or OFF by looking at the thickness of projector menu text while sitting 11 feet away from a 9.5 foot wide 132" diagonal 16x9 screen (or test patterns when standing up close to the screen). However I can't see any difference when watching a movie or video.
The RS4910 fan is just as noisy when the bulb is on HIGH as the RS1. (I like to run it on HIGH because of the size of the screen.)
I do like the 1/16 pixel convergence controls of the RS4910 that allow perfect convergence edge-edge of the image. However, the RS1 convergence wasn't exactly bad.
The RS4910 does provide inky blacks with the dynamic iris, but the RS1 already provided deeper blacks than most movie theaters.
So all this might make you believe that I wasted the money on a projector upgrade, right?
Wrong. The 3D of the RS4910 is awesome!
I followed the advice of this forum and bought 6 pairs (since my theater has 6 seats) of the "Xpand EX105BT Active 3D Shutter Glasses and Bluetooth Emitter for Mitsubishi Televisions" for only $18.99 each on Amazon. With my non-polarized mesh screen the 3D effect is fabulous with no ghosting (Crosstalk setting = 0). I have to look really hard on animated movies with solid colors to see any ghosting whatsoever.
I've been buying the 3D versions of Blu-Ray movies (including IMAX movies) for the last few years in expectation of eventually getting a 3D projector, and now I'm finally getting to watch them in their 3D glory.