I go for the coralife's as well, straight pin setup with 10ks, or recently switched to Odessya straight pin setup but 12ks (all 21" and 55w) ....
The 10ks are more blue spectrum, and the 12ks give off a more white/yellow hue....I like personally the more blue look....
I mounted them in my canopy retro style, with my "current" moon lights .....and a strip light with an extra actnic in the back.....