Room treatments - GIK Vs Acoustimac


Folks,
I would like to hear from you, opinions on treatments available from GIK and Acoustimac. I am leaning towards GIK, cause I have read nothing but very good user reviews on them. And in one such review I came across Acoustimac panels. Researched them and found that they make acoustic panels using the same material that GIK uses, but at much lesser price points. They also give you the option of buying 1 panel at a time. They are the only ones that have some eco-panels, albeit at a slightly higher price point.
128x128milpai
Agree with Sebrof. Same with my 244s. The side and back "framing" are open on purpose for trapping instead of reflecting. It is a bass "trap". Not done to be cheap, but rather for better effectiveness.
Csmgolf,i stand corrected about being corrected about GIK putting wood frames around their treatments.Thanks for the verification that they leave the side borders bare for absorption as per my original post of 2-27.
As an update, I received 2 tri-traps and 2 monster panels from GIK. They cleared up the sound stage while tightening the bass response. I do not have any panels on the first reflection points yet and that may be the reason why the imaging is not as pin-point as I would like it to be.

Can someone please suggest why people add panels behind boxed speakers? Does it help in sound stage? My mid-range is terrific and I love it. I want to get my system to a point where even when I move my head from the center position, the vocals should still appear to come from the middle. Is this possible? How should I decide between diffusion and absorption?