I went from x3 kessils to a 250w radium w/ x4 t5s on a 40g breeder and I couldn't be happier. Softies, LPS and monti caps grew great with the LEDs, but I never really got good growth/colors out of my acros until I switched.
not that LEDs can't make SPS grow and look nice, I just think that the classics (MH or T5) just make it easier to get good looking SPS. And with the amount of fixtures and light you need to equal the spread and growth of MH/T5s, you're looking at similar energy pull and higher upfront cost. Usually the best SPS LED tanks have double the amount of fixtures "recommended". If I abandon SPS, I will definitely kick the MH for Kessils again.
But the controllability of LEDs can't be beat, which might be why they are more difficult to grow SPS since people tend to tinker with them a lot.
A while back I did a cost comparison on start up cost of x1 250w radium MH vs LED and incorporating my kW price and usage (310w vs 160w), it would take 5 years for the LED to be more cost effective than MH and thats not counting change in heater usage. In the end, most people are looking to upgrade lighting after 5 years anyways.