W/o heatsinks it's not nearly as expensive.
And yea I did a bunch of testing at diff watts/height, at 18" / 35 - 40w per board works perfectly with my grow style.
That and the 301b and 561c leds have a 120 degree viewing angle, when high up the light goes all over the place. So I try keep emm around 16" - 20" and lined the tent with orca.
Keep in mind tho, I'm running 132's which are larger in size than the 288's,
less overall leds but slightly larger footprint.
I'd loooooove to see 11'ish inch square boards with the 301b chips @ 132 led count.