My 180g reef was 1000w of MH and 160w of t5 for about 3 years and it went from 75% lps and 25% sps to 25% lps and 75% sps.
For the last 3 1/2 years it's been all led with 2 EverGrow IT2080 fixtures (same as ReefBreeder Photon 32 with but with a custom led layout). After a 4-6 week acclimation my corals seemed to do just as well under the leds as they did with the MH & t5. I have about 75 corals in the tank and I'm continually fragging to keep some of them from killing each other!
Pros:
I love the push a button and change from one mode to another, especially when showing off the tank or selling corals.
I enjoy the 5 hour sunrise and 6 hour sunset. I know the corals could care less, but I like seeing the tank evolve during the day.
I save about 1/3 to 1/2 the cost of the leds fixtures in electricity used by the lights, my chiller and my home A/C as well as MH and t5 bulb replacements.
Cons:
The shadows under coral and rock ledges is an issue. I keep threatening to add a couple of t5's but it's a very low priority.
Conclusions:
Unless somebody invents cool running MH bulbs, I'd never consider going back to MH. I can buy new led fixtures every 2 or 3 years with the money I save compared to running MH.