I had the same situation you were in. Left freshwater to go salty, and originally I used the cheaper option of using T5's. In a lot of ways I find that they're highly reliable. A T5 brand with a good reputation will allow healthy coral growth.
There were a few drawbacks to the T5's that brought me over to LEDs:
1. Energy consumption - the T5's in their fixture would get quite hot as they ran all day. While it wasn't enough to cause a problem in my tank, I saw faster evaporation, more salt creep, not to mention the electricity consumption obviously caused an increase in my electric bill.
2. Horrible unwanted algae growth - When I bought a few coral that had higher light demands, I kept my T5's on more often to satisfy them. However, that led to a terrible algae spike. It took me almost a month or two to get rid of - lots and lots of turbo snails, lighting blackouts (no lights for 3 days), and even vacuuming out the algae on my sand. Was such a NIGHTMARE.
3. No ability to adjust the lights gradually or automatically - Being on a budget, I thought that a timer was a silly luxury that I really didn't need. However, when I went out for an evening after work or spent the weekend away from my tank, that meant that my lights were sitting on (or off) for an extended period of time. That's not a good thing. Plus, there's no dimmers on T5's (that I've seen!) that allow you to adjust the lighting levels instead of abruptly slamming your corals with light or immediately taking it away. Lowering the lights slowly is better for the coral and is really excellent for acclimation.
Being on a budget, I searched my butt off to find something affordable. I have a 20 gallon tank at the moment, and I bought "Current USA" brand LEDs from Amazon. I think I got the 36-gallon lighting system for $140? It hurt to buy at first, but I am SO SO happy I did. It was just worth getting rid of the headache. While I would say to peruse EBay for lighting systems as well, I've heard some serious horror stories about getting garbage from China. If you choose to go that route, I would absolutely consult one of the members of this forum first. Personally, I love my lights.
The only complain I have about my LEDs is this:
Being a 20 gallon tank with enough wattage to support 36 gallons, I accidentally bleached a bunch of my coral
You'll have to read the art of adjusting your light levels, but once you do, you never have to worry about your lights being on or off and at what levels again.
All in all, I would say don't take the route I did by trying to save $ at first, because it cost me in the long run (and now I have unused aquarium supplies all over my house). LEDs all the way
