I would say you will spend more to go with a T-5 setup. Lets face it 500 watts from t-5's are the same 500 watts from halides so no energy savings really are to be had. If you run an 8 bulb t-5 setup at 54W a bulb you are using 432w of electricity. The same heat is produced with those t-5 as with 2 250 watt halides. If you choose to overdrive your T-5's to 80W your looking at 640W. The energy savings and heat reduction with t-5's is not really there.
What makes T-5's so great is the colors you can get out of them, and of course great par and light coverage as well. Par wise if you compare most 6-8 bulb T-5's to 250W halides you wont see much difference, depending on bulbs used and placement of course. Now If we start talking 400 Watt halides thats a bit different but lets stay with 250 halides as a base model since they are the most widely used. Most of the newer (and big $) T-5 fixtures have every bit as much par as the halides would and if they are overdriven they can have more par. The lower end fixtures have decent par but have a lot of flaws, and for the money I would pick halides for sure over these. The T-5's claim to fame is the light is spread the entire length of the tank and that they really make corals pop, there is no getting around that, much better than any halides ( yes even Radiums) but it can take a lot of trial and error finding that perfect mix that you really like. But once you find that mix WOW!!! I researched the heck out of T-5's for quite awhile before deciding on lights and guess what, I chose halides as my main light source. Two reasons, one was initial cost. To buy a 6-8 bulb fixture of good quality was going to be a lot of money, not to mention the money spent buying different bulbs in search of that "perfect" look. The second reason was that for all that money spent am I really getting that much more for my tank? I decided the answer was no, especially when I got my halide fixture used for a VERY good price. I do have two 54W T-5's in it for actinic though.
All that being said for your 14" tall tank you could easily run T-5's and have SPS corals no problem, providing you buy the right reflectors, ballasts, ect. A 6 bulb setup will be good for an 18" front to back tank, and an 8 bulb would be good for a 24" tank. Sorry if I rambled or seem like a know it all but I hope I could help you decide.
