diffusers 101

Good sound doesnt have to mean ugly if your main listening room serves multi purpose. There are some attractive diffusers here http://arqen.com/sound-diffusers/ along with blueprints for building your own, videos illustrating how they work and so on. Nice find.

If you employ diffusers where do you usually find them most effective?
A must between the speakers and a the first reflection point on each side wall
plants make great diffusers...
the first reflection point concept worked poorly in my room.  Also beware of over damping...
I would of liked to try them between the speakers but there's a wall mounted flat screen in the way. That will be veiled after I have a contour put in copper pipe and braze mounts that will meet wall joists at either side. The back wall wasnt a good option for hanging two combined defusors of this size either. So after spending a couple hours over some days freshening with wood filler and white to match ceiling thats were we slung them. The results are positive.

I have a bit of a crazy idea for a treatment providing the inner wall joists cooperate. Ill have to check with the laser. I was thinking of cutting the drywall away and sinking one right into the wall. A little unconventional sure but there is method behind my madness here.       
I have watched most of the videos from this company http://www.acousticfields.com/ and found them rather compelling. Is anyone else familiar with this guy? I like the idea of embedding the diffusers in the wall that's an interesting idea. I'm just wondering if the overall plane of the diffuser is the same as the wall if that would negate some of it's effectiveness?
My way of thinking is yes, given the right material and purpose. If its flush with the wall there are no ridges or obstructions of any kind even acoustic friendly treatments can be unfriendly in some ways . I havent thought of a way to hide them, that was my main objective. After some more thought it seems like a good idea as far as acoustics go, and depending on the intended material and purpose.