Does anyone know why Decware advocates diffusion in the RFZ? Real Traps, Gik and others recommend only absorption in the first reflection points witch makes me think that maybe Real traps and Gik sell a different type of diffusion than Steve uses? I know Real Traps owner indicated that he was not happy replacing his RFZ traps with diffusion in his home.  Maybe is purely subjective and most audiophiles like a different sound than pro-audio type people but rarely do I see it recommended to uses diffusion in the RFZ. But then I see these extravagant studios with nothing but diffusion with the assumption there must be absorption behind all that diffusion. I know there has to be something to this if Steve is doing it.  

IMHO - most people don't have room enough for proper diffusion. You need something like 15' between the diffusers and your ears for them to really splay out the sound properly. That, and absorbers are so much cheaper and easier to build.

That said, I find that absorbers don't help as much in the time domain and  can take too much energy out of the room. With my Zen amp, I have only two watts to work with, so I don't want to burn up that acoustic energy in absorbers, I'd much rather install diffusers to:

#1: Break up that direct reflected sound but keep that energy in the room

#2: Adding a time delay so my ears can discern the direct information from the speakers and the reflections from the solid surfaces (walls)

Absorbers can and should be use in frequencies below what you can logically use diffusion for, and absolutely used for bass traps to get some of that puddled up mud out of the room and lessen the effects of nodes. But if diffusers are not practical or too expensive or whatever else, something (absorbers) are better than nothing!

When the room is setup correctly, you should be able to clearly hear the reverb in the recording, and it starts to wrap around you almost like surround sound. Using traps instead of diffusers can lead to a dead sounding room...granted, allows you to really focus on your speakers, but speakers are trying to reproduce instruments, and instruments don't play in a vacuum, they play in a room with natural reverberation and time delay.