Should be pretty good - it's gonna give you 48 watts on a 10 gallon. Being T5HO you would get more light in the tank than PC. Plus the tank is pretty shallow - the one thing I would watch for is coverage front to back (I would not worry about side to side) Because it's two lights, you might need to have it forward a little as that will most likely be where the majority of corals are.
I have a 4x24 on a 30"x12"x12" and everything seems to be responding well to the lighting. I have a Pinks Birdnest (SPS) that is growing well, and a clam that has put on growth since I bought it. I will say that I keep both high up in the tank closer to the light.
Most of the softies (mushrooms, zoa...) should do really well with the light.
Another thing to consider with the T5 is that you can switch up the bulb combo to get different colorations and PAR ratings. Here is a great thread to read through:
T5HO ForumI have read through a few times and just updated my lighting to give me a MUCH higher PAR rating. Based on most of what I have read, this should be better for SPS, Clam and should also provide better growth rates.
Have fun with it!