I would not recommend LED's on such a deep tank. But then again it all depends if you want to grow anything. LED's provide alot of visual light, but not so much when it comes to plants. I somewhat understand how they work wiring, mixing wavelengths, ect. When I decide to play with LEDs I plan on wiring my own. I've seen the extremely overpriced premade setups, and IMO not alot of them are cut out for being used as the only lighting. I see alot of the DIY builds online are using high powered 3 watt LEDs which seems to be working quite well for growing plants ect. These fixtures usually need multiple fans to keep them cool and multiple plugs. Here
is a really good DIY thread that also helps explain how they work and how to build one.
As far as the color mixing, of LED's it seems to depend. You can get the big 3 watt ones in white and in a number of color temps(kevlin ratings) alot of freshwater planted builds seem to use a mixture of these all white bulbs. While I see reef builds using mostly white with blue, red, and a few green LED's thrown in the mix.
Currently I'm undecided on LED's. You still need enough watts so there isn't a major reduction in electricity costs. They are expensive, even the cost of building your own fixture is expensive. The lights are suppose to last a long long time like 15 years and don't need to be replaced so that saves money. On the other hand, I would expect a fixture to have problems with wiring, drivers, and adapters after a certain age.There is alot more required to run LED's then other lighting, this should make more sense once you read the link in the first paragraph. A basic T5/T8/T12/ cp florescent is basically a plug, a ballast(or starter), end caps(sockets on end(s) of bulb), then bulb(s). They all run fairly similar, while LEDs on the other hand don't even use the same power source(DC not AC). This is why I would suggest building your own LED fixture. Its easier and cheaper to repair something you have built and fully understand, Then it is to try and trouble shoot and repair a premade one.