I have both the MMX 300 and the Forte.
CMSS-3D works rather well in games; I like it far better than Dolby's solution that I used to use with my old M-Audio card, but do keep in mind that the M-Audio card was likely an older implementation as well. (With both CMSS-3D and Dolby headphones, you will need to EQ the bass down a bit to allow you to hear the more subtle audio cues of competitive play as the MMX 300 still has a good amount of bass, though somewhat less than the non-headset version.)
Since you play an EAX game, I can see where having actual EAX will certainly be an improvement over the software implementation of EAX found on the Asus cards. Software EAX is simply not the same. That said, while the Forte's hardware is superb compared to the stock X-Fi, the drivers are no different. I have had issues, while relatively uncommon, particularly with CMSS-3D where virtual surround "channels" will drop out, requiring a reboot.
The other major issue with the Forte is that the card has grounding issues. If your Forte is placed adjacent to a graphics card or CPU, or even if the Forte's bracket contacts the bare metal of the case, EMI is readily transferred to the Forte's ground. The result is that the Forte can have a very noticeable hum as background noise during quiet points in games or quiet passages in music.
In my case, this was easily remedied as my case has a painted back bracket. Thus, I simply added rubber washers between the screw and the Forte's bracket, and the hum was gone. (Others have needed to tape the surface of their Forte's bracket.) The Asus cards do not have these problems as they are properly shielded.
All this said, both the Asus and the Forte drive the MMX 300s very well (as will most amplifiers), and I do really like the Forte. Granted, I too got the Forte for EAX with legacy games. Given the Forte's few quirks from driver and grounding issues that you must work around, at first, however, I can say hands down that if I had no need for EAX, the Asus would have been my card. The Asus cards simply have far fewer issues.
Oh, another minor annoyance that I have with my Forte versus the Asus cards is that the Forte requires a breakout cable for the mic whereas the Asus cards have both the mic and headphone jacks on the PCB.
I hope this helped.