I run a 600 HPS in a cool tube...
I also have a 600 HPS in an easy 8 reflector...
They both work wonderful...!!!
I can put my face to the glass ON BOTH and not be bothered by heat...
a bit bright... but deff. cool to the touch...
Now... when it is time to do anything around the op. it is so much EASIER to get around the cooltube than it is to get around the HUGE reflector, that it is not even funny....
I will say that a stock cool tube will not compare in foot print with the bog honking reflector... but...
As Al B. Fuct illustrated, if you remove the internal reflector on the cooltube and mount it to a BATWING style reflector, you actually have a BETTER reflector....
I would go with cooltubes ANY DAY.... and if doing multiple lights in a row, I would really consider the big tubes... I have seen up to 3 lights in ONE tube... as well as the shortys in sequence with ducting...
My 2 cents... one of thse WITH THE COOLTUBE....
http://www.gchydro.com/Adjust-A-Wing+Reflector+Kits.html
http://www.homegrown-hydroponics.com/904545.html
http://www.specialty-lights.com/adjust-a-wing-reflector.html