Which will be less heat do you think?

3 x 23w

or

1 x 42w
1 x 23w


(guestimation)

those cfls will barley put out enough to make much of a difference work out which has more lumens and go with that 1

As heat loss is related to light loss, the answer is that 1x42 + 1x23 will be less heat due to wattage alone. As stated, you'll need more watts though. You could veg a plant slowly with that wattage, but will need to consider doubling/trebling it to flower unless you are happy with 1 small plant and not much to smoke.

I had 4x23w CFL in a little plastic cupboard without any heat issues. I now have 2x85w and it will hit 91 if I shut the door. What are you putting them in?

i have a box thats only sizable for 1 autoflowering plant. i believe 3 lights should be more than enough in such a small containment. my debate is having 3 23s horizontally that gives light from top to bottom or having a big 42 vertically that will give light sideways