FWIW, I love my 150w pendant over my 75P, perfect amount of high light. Check my sig.
I've previously gone through all versions of your set-up!
Looks very nice where it's at now. I bet it looks amazing in person. They all looked good IMO.
The only main reason for not going MH is the damage it would do to the hydro bill.....otherwise that would probably be my first choice. The sunrise/set feature with LED's kinda sold me.
Thinking roughly (no real math done yet) 45 x 18cm for heatsink dimensions suspended anywhere from 15cm to 30cm. Having trouble finding examples of other builds with a similar tank footprint. Anyone know of any?