Hi,
I was following this thread since few days. I have 55 gallon, 48" x 13". I was in market to upgrade my lights, had power compacts with 4 65w. was looking to get something metal halide. Saw this marineland pro and my LFS also recommended it. I was concerned it being little wider than my tank. My LFS ordered it for me and matched the internet best price. anyway, I installed it yesterday. This is what I have experienced.
The light looks extremely beautiful. It is little wider but thats ok. It is very bright and my corals and aquarium are looking beautiful. The legs are steady. I like this light very much.
tlsims the light you bought with your aquarium is almost same as marineland, I think the only difference is that marineland one has digital timer on it. I think if you just replace the bulbs, you should be fine.