Yes sir, a little warm-up and you're pretty much good to go.
I do perform better in cooler temperatures, so yea I also start to prefer it to the summer heat.
:hump:
600w at 50% with good coverage in a 3x3 sounds about right. that's 50w per plant, and should be more than enough.
I'm currently running four boards 220w with full spectrum in an 8x4, I'm at 630 Watts and that's fine.