Having grown for a few decades and had it to do all over. The first thing I would buy are real good meters.
With hydor you out for the max output for the bitches. I would guess that it would take about one crop to pay for a good meter by maximizing the potential of the plants. (if you only had 2-3 plants)
2 filtering system with good flow into the space.
3 good ferts made for pot plants Its about 1% of growing cost
Not much has changed over 30 years of growing.
With the exception of people getting screw, by B.S. sales of B.S. POT lighting systems.
It all gets down to Grams per Watt per Month
1000 bulb producing 1000 grams in 2 months = .5 grams per watt.
Thats the bottom line, no more , no less.
From florsent sticks to hid light, its all about tweeking to the max output.