Having tested and used all 4 main VSS technologies extensively, here's my summarized view on them:
*note*
Not all VSS technologies work well for all types of headphone, for example Dolby Headphones does not generally work too well with most closed headsets/headphones. This is due to the reverb DH has and having a closed headphones bounces the "echo" effect, leading to what many refer to as "like being in a tunnel".
CMSS-3D
They still have the best positional cues over amongst the 3 VSS technologies, they are still the ones to go for if your primary needs is absolute positional accuracy.
The downside of CMSS-3D is that it makes the audio sound overly thin, it's worst especially if you use it with bass-shy headphones and even more so if they're open ones. Though there are people who do feel that the "tin can" effect does help even more with positional accuracy as it accentuates the mid-high frequencies, leading to picking up audio cues around the player.
I for one personally think that if you want CMSS-3D to behave like an all rounder, you'll want to use a closed headphone/headset and do at least have tight bass.
Dolby Headphones
They're honestly the worst VSS tech in terms of positional accuracy IF you're using it on a closed headphone with relatively narrow soundstage. Many people do not understand that for DH to shine, open headphones with decent soundstage and some possess at least some tight bass is a must. I use DH with a HE-400 and K702, they're just SWEEET. Positional accuracy is indeed still not as good as CMSS-3D, but the immersion I get... I'm willing to look that off.
Because of this, Dolby Headphones generally work nice with movies too. Much better than CMSS-3D at least.
THX Surround
I don't know what went wrong with THX Surround honestly because what I feel is that it is very inconsistent. In most games, THX surround just doesn't project proper positional accuracy but instead over emphasize on immersion. I honestly only found THX Surround usable with Battlefield 3, I don't know why... but any other FPS or games, THX surround just sounds dull... lifeless.
Some users do however feel that THX Surround provides the best immersion and is good for movies, I personally don't feel that way as I think Dolby Headphones fits that bill better... for me, at least.
SBX Surround
It's been quite on the upward spiral lately, what THX Surround did wrong... Creative took it and modified whatever they needed to and the result is something I would call: the marriage between Dolby Headphones and CMSS-3D.
SBX does not have better positional accuracy than CMSS-3D, but it IS better than Dolby Headphones (even with a good open headphone combo). It doesn't present that "tin can" effect or have too much reverb.
Best of all, I feel that SBX Surround just works with any type of headphones. Be it open, semi-open or closed. SBX fits well within the range and although it doesn't get to be as accurate or as immersive with CMSS-3D and DH, I think SBX is the best all rounder for someone who just wants to game and watch movies.
I hope that helps. Remember, virtual surround sound DOES work. People who say it doesn't, well... too bad, it doesn't for them.
IMO, they work and they're fun to use.
