Personally, even when I tried running a refugium, my SPS were just OK. When my chaetomorpha started dying my SPS colored up nicely. I haven't seen an SPS dominated system with blazing colors yet that relies on an ATS. I'm not saying they're not out there, but (AND THIS IS MY PERSONAL OPINION) I feel they can yellow out the water, inhibit light penetration and basically give a false sense of how low nutrient of an SPS tank you're really running.
Way OT but I just saw this one earlier: http://www.reefcentral.com/forums/showpost.php?p=17449792&postcount=3
I realize this system isn't ATS only, but there are pics of his scrubber in the thread and it is obviously growing well.