Grams per Watt... nothing will beat HPS... that is why commercial growers of all types of plants use it...
Grams per Watt... that is what makes your home grown cheaper or more expensive than street value...
I know initial cost is a factor... but if you are between 20 and 30 and see yourself growing for the next 10 to 20 years... the initial cost investment and savings disappear....
In the long haul, we are all trying to improve how many grams we get for every watt ($) we burn...
For a small grow... NOTHING will beat a 400 HPS... not even 2 X 250 HPS...
The 400 and higher lights have more intensity... the light "hits harder" kinda thing...
Put a 400 in a cooltube with a good fan and you can have it 6 to 8 inches from your plants... let's see a 400 watt CFL 6 to 8" without ventilation... you are going to have trouble... You will need ventilation no matter what...
Sure the HPS is going to require better vent... but the outcome more than makes up for the trouble and expense...
Just my 2 cents... and yeah.. upgrade 2 times... not 15... that saves a pile of cash too...
Gypsy...