The major difference between the two is that the Icecap balast in the second link will overdive the bulb. What this does is gives a boost to the output and intensity of the lights. However it comes at a cost of life of the bulbs. I've got the SLS T-5's over my tank (5x24w over a 29gal) and do pretty well with my SPS and I've got a clam in the rockwork about half way up. I do keep SPS frags on the sandbed, but only durring light aclimation stage I don't think they would do great down there with the exception of most montis. IMHO if you are wanting to keep SPS and clams at the sand bed the Icecap's are going to be needed on a tank that deep, and even then I'm really not sure. You're best bet would be to go into the SPS forum and ask for people who are currently doing a similar setup. And be prepared to get bombared with the question "Why not just use MH?"
Is there a reason to not use MH? I'm only asking because I've only seen a handfull of tanks that size with T-5's. A couple of them were the really nice with great color, but I think a lot them were also useing Zeo. setups.
