DOF H3-h6 questions, chair models, buttkicker and other things, or other brand/type?

I was reading reviews of the OpenWheeler seat on Amazon, and one person wrote the following:

“Downside is the rails… they are useless as it only locks in one side - so no matter how you assemble it, it will always be flimsy and shaking around on your right side. If you want a stable seat you will need to buy accessory rail.”

Is this a legitimate concern? I ordered an H3 and hope to find a seat that works without problems. I’d appreciate any thoughts or response to what this reviewer wrote. Thanks!