I won't answer all those questions regarding this new item since it ain't out yet, and it's best just to wait until all testing is done.
As for VSS solutions: my faves in terms of tricking my brain and accuracy:
Virtual surround accuracy. Spots 1-4 are so close to one another, you really can go with any and get a real sense of surround from all sides
1. GSX (One + symbol on the GSX1000, which sounds like 2/3 room size. Two ++ symbols has too much reverb)
2. Dolby Headphone (Dolby Headphone 2, which is 2/3 room of it's surround. DH3 too much reverb. Overally, despite its drawbacks, I find it very accurate in surround positioning)
3. Audeze Mobius (default is 35% Room Ambience, I'm using 41%, this sounds closer to DH2 and GSX one +. 50% and up has too much reverb. The more I use it, more I feel that Audeze got the surround right ALREADY.)
4. SBX (rear cues a little closer to you than the top 3. Farther = easier to discern front and backl, though SBX is still stellar here. SBX has the least reverb and can maxed out at 100% for the surround without drawbacks)
5. THX TruStudio (like SBX but IIRC, the off angle positional cues weren't accurate. So a 1 o/clock sound cue sounded closer to 3 o'clock, etc.)
6. Razer, CMSS 3D, the rest. I only briefly tested these under HeSuVi and didn't like them. I can't say much as it's the least experience I have.
Worth noting:
https://fongaudio.com/out-of-your-head-software/
Darin Fong's Out Of Your Head has various virtual surround emulated speaker setups that sound EXCEPTIONALLY good. It works. Problem is, it's software and limited to PC. But having used it for a bit, it definitely belongs on the list. I don't have enough experience with it to say where I would place it, but if you're PC only and don't want devices, it is a good alternative with some presets having really good cues, and others not so much. There's many to play with however. It's a bit costly though for just software, hence why I didn't put much focus on it when I was in direct contact with them. I should've gone more in depth. That was a different time and me.
Virtual Surround Sound Quality
1. SBX (cleanest sounding)
2. GSX and Mobius (comparable in quality of the sound)
3. THX Tru Studio (despite weaker cues, the sound quality is good)
4. Dolby Headphone (infamous for being a bit too reverb heavy, and distinctly warmer tonality compared to the others.)
Overall
1. SBX (I feel it has most of everything)
2. GSX (Until it's available on consoles, its use case is too limited
3. Mobius (Like GSX, its limited to PC which is a shame, as it is exceptionally good)
4. Dolby Headphone (it's positional accuracy is top notch, but the sound is heavily colored and echoey, so it's polarizing)