I have been using the Creative X-Fi Titanium (Non-HD) for some time now. I do a lot of PC gaming, but sometimes it is difficult for me to determine whether or not CMSS-3D is making a difference in certain FPS titles I play...
1. Team Fortress 2
I used to play this game a lot, turning CMSS-3D didn't seem to change much audio wise. This is before I figured out that Creative Alchemy is needed to restore anything running off the Source 2 engine. I still can't figure out how to get Alchemy working with this particular title, as I've read conflicting instructions on how to do so.
2. Killing Floor
I play this game more than any other game. It runs off the Unreal Engine 2, so I thought my X-Fi would benefit it greatly. However, this game is a little rough around the edges in certain ways. The most glaring issue is that when enabling sound hardware acceleration in the game's .ini or in the in-game menu under audio system driver a BSOD occurs every time. This is well documented amongst the Tripwire (development company) and Creative forums. So, I use the lesser quality software accelerated support, which CMSS-3D seems to benefit to a considerable amount. However, I'm frustrated I can't take advantage of my card in the first way. And I also cannot figure out whether Alchemy would make things better yet. I assumed because it uses OpenAL natively, it wouldn't need Alchemy; but this page seems to suggest that Creative Alchemy benefits Unreal Tournament 2003, 2004, and 3. Which I assumed wouldn't need Alchemy because they could they used OpenAL natively? And since Killing Floor is a mod of that game, this could change. And since I'm using software accelerated support maybe that wouldn't matter anyway? I found one person in a Tripwire forum who claimed Alchemy benefited this game, but that the buffers, duration, and maximum voice count settings in Alchemy caused wild fluctuations in game performance and he/she could never tweak it right.
3. Chivalry: Medieval Warfare
This one I've been getting into recently. This is game is even more rough around the edges than Killing Floor so I knew I would have questions about it. I would think that it would be once again natively supported, because it uses Unreal Engine 3, but it does not give me the same "exact coordinates in space" feel that the CMSS-3D in Killing Floor gives me. I haven't found any instructions on how to get Alchemy working with this game so I haven't touched it yet. But I thought I wouldn't need Alchemy for an OpenAL game!?!??!
4. Battlefield 3
Turned on CMSS-3D for this game and HOLY SMOKES. I can hear everything in every 3D place. Too bad I NEVER play this game anymore.
So today I started doubting whether having a Creative card was worth it. I could just get a Xonar card and flip on Dolby Headphone. Sure I'd be getting average surround sound, but I wouldn't have to worry so much about getting things working perfectly with legacy titles. It is my understanding that Alchemy is rarely used for newer titles because most audio in new games is software-accelerated.