The Titanium HD is indeed still better if you count the fact that the Z does color the sound a little bit.
Only matters in music though and only really relevant if you're freaking picky in your music. The colorization is a bit on the treble side, on the upper mid-range.
Again, personally... I literally "hear" the issue to be quite honest.
Otherwise, the Z is as good as the THD for less money (unless you get 2nd hand) in games and movies. In fact, I actually like the Z for games better even if it doesn't has as good as a virtual surround DSP... in terms of positioning.
CMSS-3D, I've been on it for 8 years so I know how it sounds the moment I hear it. Positioning is indeed the best I've experienced with and I've tried Dolby Headphones and Recon3D (omygod.. don't get me started on this piece of trash). But the fact that it sounds really thin and like I have cardboard box on my head, it's deal breaker for movies and many SP games.
Great when I play MP FPS, but that's about the only damn thing it's good for unfortunately... at least for me.
Dolby Headphones sounds so much better for movies because it is based on 5.1 surround speaker in a room, it's more immersive. Everything is a lot more full and that's why I've always stuck with Dolby Headphones for movies and SP games. Problem with DH is, it lacks in positioning to CMSS-3D.. a lot. Can't use it for MP FPS at all, no way.
So what about the Z's SBX Surround then? I would say it's the middle ground between CMSS-3D and Dolby Headphones. It's immersive enough that there isn't the "cardboard box on my head" sounding issue, but not way too full that it hurts positioning by a lot. Although I still find myself going back to Dolby Headphones for movies, but for games... both on SP and MP type of games, I find SBX to be best fit for it.