GIK is great and about middle of the road in pricing compared to others. You should consider their corner traps or soffit traps, as well as their wall panels. Many of their panels and corner traps have diffusion plates that can be added. This gives a balance of bass absorption along with scattering of high frequencies.
Yes, the ceiling and floor are much more important than most people realize and complete the illusion of your room vanishing and leaving only the recorded space.
ATS is a less expensive alternative.
One other thing to consider is that GIK is running about 8 weeks to delivery.