I picked up a Santa Cruz yesterday to see what all the fuss was about. I don't know where to locally pick up an Acoustic Edge so I didn't get one. I'll run through the strengths first so people don't accuse me of being bias. All testing was done in win2k as that is the only OS I use.
At $70, this card was considerably cheaper than the Live!, so if you are on a budget, your choice is already made up. Audio does sound better than the Live 5.1 Platinum when using a set of headphones. Does it blow away the Live? Absolutely not. Don't believe the hype. The differences are subtle. The Cruz's sound is sharper and more in your face, while the Live is a bit smoother/muffled depending on your point of view. The cruz has a really nice hardware 10 band equalizer, this is probably my favorite feature. It allows much easier sound adjustments than the Live. The output options are easily manageable and customizable in the control panel and quite full featured.
Now for the problems. First off, when you open the box, you see right away how TB can sell this card for so cheap. All that's in the box is the card, a 4 pin CDROM cable, a driver CD, and some stripped down audio program I've never heard of. This compared to the SBLive Platinum which comes with basically every cable you will need, and a software bundle that is second to none by a long shot. The CD that came with my Cruz card didn't have win2k drivers at all on it. Trying to run the setup gave me a wrong OS error message. I had to go to Turtle Beach's site to get win2k drivers. Using the digital coax connection to my receiver, there was no descernible difference at all using my speakers. Turning the volume knob all the way up revealed no hiss at all from either card. The lack of an optical connector for me is a pain, because my receiver has multiple TOS connectors, but only one coax which is occupied by my digital cable receiver. I found all the effects that can be added to outgoing sound (EAX equivalents) sounded like ass to put it bluntly compared to the Live. Not that I ever used them on the Live, so not much of an issue to me. The 3d stereo enhancement was so horrendous, I don't know why they even include it. I could not get dolby digital audio for DVD's to work in any form whatsoever with this card. So if you want to watch movies in win2k, you're not getting DD. I've gotten used to the convenience of the front mounted connectors for the Live, I had forgotten how much I hate digging behind my case to feel for the right connector like I have to do for the Cruz. One oddity I have found with the Cruz is that using Winamp mp3's play magnitudes louder than any other audio source. I don't know what causes this, but it is rather annoying to have to adjust volume levels whenever I play mp3's and then stop playing them.
Am I keeping the Cruz based on its strengths and weeknesses? Yes, but only because I have a second system to put my Live in, otherwise I would have returned it. I mainly use headphones on my primary system, and the Cruz sounds better that way. The lack of an optical connector is not a problem, since I can use the Live for that purpose in the second system and it will sound just as good as the Cruz. I've also moved my DVDROM drive to my second system, which is where I wanted it to begin with, so the DD problem isn't relevant either, though I don't actually ever use my computer for watching DVD's except under odd conditions.
If you already own a Live! 5.1, I wouldn't recommend changing cards. The audio differences aren't significant enough and your live is far more flexible. If you don't own a Live, the choice is not so one sided. The significant price difference has to factor in if you are not interested in the Live's software bundle or additional cables. Based on a features list, you can compares those yourself and decide which fits your needs better.