I've been using PC lighting for so long it would be hard for me to use anything else, I still use the wpg rule. Those are nice fixtures are you running 2 of them on the tank?
Deep tanks need a little more juice in the lighting department so the MH will come in handy for a hour or 2 each day, if you need a boost for growth or to keep the Discus warm. I have always had good luck trying to copy natures lighting with a sunrise, to full power, back to half like cloud cover, then lights out at lunch for an hour, then back thru the routine til night. Some might think it's nuts, but it allows you to have light in the morning for feeding etc, the break in the middle of the day is what the plants seem to really do well with, and then you have extra viewing into the evening when it's time to relax, then don't forget the lunar cycle, I love to see the loaches feeding at night and I think it may help with breeding as well.
I would like to learn about the LED lights, less heat, less power consumption, and longer lasting is the big thing, maybe on the next build.