yea i would keep the 2 600s, I also use to run 1 1000w hps but have since changed over i now run 2 600s also
and i like it way better more yeild and more light coverage with 2 bulbs since i ca place 2 bulbs in different places
that gives more lumens to other plants that were getting shaded before with the 1000w, the only difference i see
is the size of the buds. with a 1000w you will have bigger buds 600w smaller buds but more of them since you could
move the lights around to maximize coverage area