At some point in the future... near future, I'm hoping, these arguments will become moot. Someone is going to come out with a scaleable, reasonably priced LED lighting solution that provides both the even, shadow free blanket of light that is unique to T5's, and allows for the shimmer and contrast of spotlight lighting such as single point LED's and Halides.
We're just not there yet.
LED's have gotten very good... and VERY expensive. If you're lighting a small tank, hey, go ahead and buy that Radion, or whatever high end LED. You're lighting a large reef? I don't know about you, but I'm not willing to spend several grand on multiple high end LED fixtures, and I don't want the 'array of lights' look, either.
Halides are wonderful, I ran them for many years. The problem has always been heat, and it's not going to go away. As energy becomes more and more expensive, these become less and less viable. Honestly, LED's do a pretty good job of replicating the 'shimmer' of a halide, though they do much less a good job of imitating the reflected light from a good halide setup that blankets the tank.
Combination? Great! Best of both worlds... and you pay through the nose for it! LED/T5 (the energy and heat problems with Halides don't lessen when you add T5's) combinations look great, work great, give you both the even blanket of light, and the spotlight effect... but seriously... $2,200 for a 4' Aurora? $1,900 for a 4' ATI hybrid? Over a grand for a AL T5 + some decent LED's?
My tank is 60" x 30". I'd need, what, 4x Radions? 3x AP700's? Just can't get there.
I came very near buying a new ATI 8 bulb T5. The main reason I didn't wasn't price, but the fact that they're shipping them in polished metal finish. That's the very last thing I'd want hanging over by tank... I would have had to spray paint the darned thing black
Ended up finding a 4' 8 bulb TEK fixture that looked like new, put in new ballasts, new bulbs, and spent half of what the new 8 bulb ATI runs.
I'm hoping to be able to replace it with that ideal, reasonably priced LED fixture that I'm _certain_ will be available at some point in the future.