That's a nice idea about splitting the closet up. My question, would it be better to split it in half side-to-side (2.5Wx7.5H), or top-to-bottom(5Wx3.75H)? There's advantages to both. If I split them up, I could use cuttings and keep a few going all the time.

I don't understand the ballast stuff. Maybe I should google the innerds of a HID lamp!

Lastly, I have some CFL's now that produce around 10,000 lumens. I could easily suppliment the 150W HPS with those. So if I split the closet up, then I would use the 150W HPS + CFL's on the flowering side, and my 250W MH on the veg side?