The Audigy2 has much lower CPU utilization than the SBLive. It was immediately apparent in all my games. All of them play smoother and faster.
I opted for the Audigy2 Platinum. While expensive (relatively speaking), I really like the front panel controls. Having a full size headset plug and mic plug, with separate gain controls, and the 1394 firewire really has made it worth the price for me.
Signal to noise ratio of 106db is better than most high-end consumer audio gear.