Strictly speaking, yes.
Putting more solid boundaries and objects between and amongst the LCR channels adds to the pile of unknowns when you are trying to predict an outcome. The end result is a couple of towers similar to the footprint of an EP800. I shifted them back of the plane of the main speakers to reduce any interference as much as possible by 5 inches or so. They are concrete, so they don't really store or absorb much energy (inert.)
You can use some 2x4s or other framing as needed to make the stands sturdy. In this case, I was basically 50$ plus taxes for the experiment and some sweat.
More of a quick solution than a pretty one I admit. But they are behind a screen wall in this case.
I do not perceive the cinder blocks had any negative effect on sound quality. I think the little bit of overhang they eliminated by removing the floor loading really opened up the rest of the frequency range. Pretty sweet.
They make a square tower 16" x 16" when stacked with the honeycombs vertical.