i think its a no brainer that adding more light should increase the overall size and density of ur buds when finished. More lumens the better. The only issue that becomes when switching on that 600 watt is heat, period. As long as you have a cool fresh source of intake are and vent it accordingly it should be great. By the way man fantastic looking plants you got there. just dont make the rookie mistake and chop them hella early. let them hairs get nice and brown.