Out of the Box Picture Quality
With this projector we have to address 1080p and 4K content separately.
The short version is that as we expected, the RS400 had some rather fine looking color right out of the box, although reds are a little strong in the darker ranges.

The RS400U exhibits impressive "right out of the box" color. Image from Guardians of the Galaxy
Rich colors, deep blacks with only that touch of the darkest areas having a little red in the blacks, combine with really good skin tones. Gamma is a bit low, but a quick adjustment solves that as well.
Didn’t mean to get this technical at this point, but JVC owners tend to include a lot of serious enthusiasts looking to perfect the color.
Animation is slightly brighter than the other modes, but slightly is the operative term. It’s also a bit cooler which, if you aren’t trying our adjustments, you might prefer for sports viewing, where a little too much blue is generally preferred over too much red.
How things have changed in the last 5-6 years. Before then, most projectors, even in this price range usually needed some significant adjustment. That’s certainly not the case here. BTW Mike points out that his settings for the CMS are minor enough that the change is barely detectable when viewed!
Important to note, Mike only calibrated the projector in 1080p. It’s a whole other story when viewing 4K content that is using HDR.
Sadly, the overall picture – out of the box - for 4K HDR content is rather poor!

DLA-RS400 Skin Tones
I have to get picky when talking skin tones here. Picky in that they start off already really good. Pre-calibration you might notice the excess reds in very darkly lit faces. Post calibration that is really gone, although the slight bump in the lower mid-ranges may barely give you a slightly ruddiness. Of course calibrations will vary, and these fine points I’m talking about are probably within variation in color from lamp to lamp, and will change as the bulb ages.
In other words, don’t sweat it. Count skin tones as rather excellent.
But that’s if we are talking 1080 content, not 4K with HDR.

Out of the box skin tones with HDR content (4K)
If you look at the Skin tones while viewing a 4K HDR movie content (all three 4K Blu-ray UHD movies I own are in HDR), without JVC’s settings recommendations, then what you end up with is best and most simply described as pale and significantly under saturated.
On the other hand, with their settings, and further tweaking of the color saturation control, skin tones now look reasonably saturated, and overally really good. As I said, a true calibration would likely yield even better results, but as noted, we haven’t tried to. I assume JVC is providing their calibration software to help out, because HDR is new out there, and I’m not sure if most calibrators are in a position to calibrate HDR content.

RS400 handling 4K HDR Blu-ray UHD using recommended settings