My 3-day update:
Replacement 'S appears to be working properly now.
First session in E: D it kept reverting to head-in-lap view, multiple presses of F12 were required but after 30 minutes or so, the F12 key didn't reset the view.
Next session, however, I mapped a HOTAS key to "reset HMD" and only required to press this once and it worked absolutely as intended, so all was good.
I'm using the T16000 HOTAS and mapping the key bindings is taking a long time...
This morning's session was brilliant in the 'S. It worked snaglessly and only a few key bindings now to set...
The visuals are amazing in the headset. Clarity and brightness are superb. I really don't know what other early users were talking about on the lack of black - since this is my first HMD, it all appears to be fine to me.
I haven't messed around with any graphics settings at all - just left the defaults when I installed E: D on my new PC a couple of weeks ago. However, HW monitor has logged a max CPU temperature of 82degC this morning, so I may have to drop some settings for longevity of the CPU. (Machine spec: Ryzen 2600X standard cooler; Vega 56 Pulse; 16 Gb Vengeance 3000 RAM; Gigabyte Aorus B450; WD SSD)
Audio is a "little bit" lacking, but that's not a criticism, merely an observation, because I prefer the open speaker design by far so I can also hear real life happening around me when necessary... just a touch more bass would be nice - the AspX on boost lacks the screaming effects you'd get from full size speakers, but overall I'm well, well impressed by the 'S
Playing in VR is also a compromise. Some things aren't as good or as user friendly... GalMap and Sys Maps are "nice" in VR, but lack the usability I'm used to on a screen. You obviously can't take notes like I have been doing for the past 9 months on my DW2 expedition on PS4, but I guess the better PC logs and third party tracking software might make up for most of that, if not all of it - for instance - taking notes of interesting sites and where to find VO ice rings, etc... And of course the graphical quality in a "budget" HMD can never come close to a good monitor, or even a big HD TV.
The positives outweigh the negatives - for me, so far - but not by a massive amount. It's all in the ability to look around naturally. Definitely need a good HOTAS to enjoy to the fullest with lots of keys and a usable key binding set up.
Edit: I'm also using a powered USB hub to connect the HMD (and also the T16000 stick and throttle), and set the USB to disable power saving on the Rift S hub