Yea what are your temps sitting at? I think that is my biggest concern with Solarstorms.. I've heard they are very quiet, which means your fans are either: high quality, running slower, or Im thinking both.. then you tack on the UVB bulbs the last 2 weeks... shwoo... Idk, may work in your favor with the CO2.
I am still considering the SS400w, but you, my fellow grower, will be a determining factor- A51 is happening. period.
But the SS400 has not left my mind as a killer Flowering Panel.
EDIT: ...And Frank is dead on with 18", he's pushing 1074 umoles- with 90* lens, any closer he may start to bleach..