Just saw this thread, so sorry for the late reply. Let me just say this about T5, if you have the correct set-up it will do you wonders.
With that being said, there are all types of option out there for T5 lighting...but you have to know what you're buying before you actually buy it. Personally, I think the only way to go is to use an IceCap ballast in conjunction with IceCap SLR's. The reason behind this is because IceCap ballasts overdrive a T5 bulb, the life span is a hair shorter but the results are worth it. The IceCap SLR increases the intensity of the bulb some 85%.
The problem that I had with T5 was that I did NOT do my homework (I also inherited the 8x54 watt fixture when I bought the set-up). I had some off brand fixture that had workhorse ballasts and did NOT have individual reflectors for each bulb. Sure, it kept stuff alive...but nothing was thriving like in others tanks.
Now, let me say this about your Coralife fixture...also this isn't the gospel, just what I think. I do NOT think that you'll get the results that you want out of that fixture. First, the bulbs are not good High Output bulbs, they are regular T5 bulbs. A good bulb is ATI or anything German. I would use the Coralife fixture for over a small refugium, but not a display. If you're going to do T5..do it correctly and spend the extra money on SLR's and a good ballast.
My advice to you would be to get an elctronic 175 watt metal halide ballast (ARO or IceCap) and use that. Get a nice bulb, Coralvue Reeflux, XM or Hamilton (my personal favorite) 14k or higher....with this K rating you can avoid any type of supplementing light, like VHO or T5. Metal halide are cheaper to buy up front than T5 too, although the T5 are cheaper and cooler to operate.
If you have anything else let me know
Travis