About to invest in room treatments; GIK, RealTraps, DIY -- what is your experience?


I'm reaching the point soon where I'll invest in some treatments for my two channel listening room. Standmount speakers with tube amps. Room about 28x14ft with low ceilings, 6.5ft. Probably different kinds of treatments are needed. I'm not exactly sure yet what I'll need or how much to spend. This is not my final listening room, but I won't be able to configure another one for a few years.

I've seen many people tout GIK on this forum and I'm already communicating with them a bit. I will also reach out to Real Traps and possibly others. I do not feel bound to go with just one company or solution, so if you've mixed and matched, I'm curious about that, too.

Any recent comparisons between these two, or others? Do you have stories of good or not so good products or service? Any comments about the value of competing products? I'm not super handy or have a lot of free time, but DIY is also considered. 

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@nolo and @pdreher  Thank you both very much. These are especially useful.

@papafrog Thanks. A "tunable" idea sounds attractive.
Thank you for the links. I cannot figure out how to get rid of a couple really persistent nulls.
I have 3 art panels rear walls look good too as well as curved bass absorber diffusers in rear corners. 
Diffuser and bass tritraps on first reflection points and some in front corners too. 
Large leather g plan sofa. Thick carpets... And other furniture cushions used to further clean image. Should have something on ceiling 3.7m up... But cornicing too pretty to mess us. 

Helps with sound imaging all of it... https://imgur.com/gallery/B6BV1rW
Hifi room https://imgur.com/gallery/bRKSwoW