Mine was 60 months before cost recovery, but I estimated $10,000 for the LED setup, as I'd need 4 of them to cover the area I'd guess. Maybe 3 and then that would drop the months down a bit.
My Biggest issue would be the temp being more stable. But with an enclosed hood I may still need a chiller, my chiller right now almost never shuts off, with all those lights in an enclosed hood. I think if you can get away with only one fixture and have an open top these are hard to beat.
I know initial cost is high but the long term is really important with these things.
I can't wait to see one on a tank locally and get real info and touch the top for myself to see the heat generated.