I've owned everything form SB 16 ASP to SB Audigy 2 platinum. I've had a go at Audigy 4 and the new X-fi here at work, and I can't say that I'm at all pleased with the performance. I've never felt that the Creative WDM drivers were stable enough for DAW work, and I've never thought much of the sound recorded on them either. Too much noise, system crashes, it all depends on your system and what software you use offcourse, if you got a system that works for you great! but I'm not gonna pay out 200$ for a soundcard that is outperformed by a 80$ one... and as I said, that is just my experience and my opinion. You are free to disagree with me.
I used to pull my hair out working with my audigy 2, I got an average latency of 35ms at 48khz using WDM drivers, a -50db noise floor, the SPDIF was not digital, it got a D/A - A/D conversion before beeing stored in the system, I could go on and on, but as soon as I bought my Terratec, all problems went away... 5ms latency @ 48khz, about -90db noise floor, real SPDIF digital, 1/4" balanced inputs... and it costs 70$ I payed 215$ for my Audigy2 Platinum....

Doc-Z