[johndykstra]

I'm assuming tha by "mirroring" you are including the back ceiling vault and back wall as well yes?

Having said that, I would make the back wall corner traps thicker, super chunks even.

On the side walls towards the back wher you have 3 traps, you may want to consider two traps per wall, with them staggered across from each other. Meaning if the left wall starts with a trap, than the right wall starts blank, and repeat. It appears as though you will be tracking back there, and you may not want it to get too dead. Those blank wall spots, along with some space on the back wall, would be a good place to think about diffusion.

Also, be careful to not have a strip of untreated wall surface running around the perimeter of the room near the floor. You may want to make the traps a bit taller, to avoid too many bare parellel surfaces.

Looks great by the way, have fun in there!

edit: also consider moving your mix position back a bit, and maybe soffit mounting your monitors.