i'v had good turn outs with the 4100 kelvin bulbs. i use 12 x 100 watt cfl for veg and then i add 8 2700k 100 watt for flowering for a total of 20 100 watt cfls for flowering. little late to the post but someone else might find this usefull. and this is for 5or 6 plants
i do agree that 6500k...