I guess it all depends on what you're looking for ... or not looking for. The bacteria to sustain the tank with fish and inverts is likely needed on some kind of substance. Without LR
, that leaves you with sand, sponges, bioballs, or other synthetic bio mass IMO
. That leaves my mind with more problems hiding all that stuff so it doesn't take away from your main display. So you'd have to have a large sump or wet/dry to hide it all.
As far as enuf bacteria living on plugs... that seems to require more "shelving" in the tank to place the plugs on. That picture doesn't look as good either to me.
Now, if you're NOT looking for aesthetics, and just want a tank that "functions", I'd guess any combination of shelving and plugs, or bio-media won't be a problem for you.
It's just that in my mind, it ain't natural so I'm biased there anyway. Aside from my personal bias, the plugs and (likely) light grid constructed shelvng that holds the plugs don't seem to be enuf surface area for the bacteria to establish in enuf of a quantitiy to provide any real reef tank support in my mind.
Maybe I haven't given much real scientific proof to support my answer, but I'm sticking with it.