A pod hotel made of plastic is not much better than highly porous live rock. Or even a sponge from an HOB external filter. I would never buy one of those.
I have a red mandarin i relocated from my main DT plumbed into a 15 gallon tank, sharing a common sump. I put my sensitive small critters that I want to observe closely in the 15, where it has milder flow for my red mandarin and 2 pairs of yasha hasha gobies each paired with a red banded randall's pistol shrimp amongst my frags from my DT.
I have not seen the red mandarin ever eat anything in the DT nor eat any foods I give the gobies and shrimps in the 15g. He has been with me for over a year now. 6 Months in the new 15 gallon tank. He is not skinny, but he is not plump either. His belly is slightly rounded, convex and not concave/sunken in like a starving fish when I first got him. But he has started to develop the long finnage of a male dorsal fin, so I know he's healthy.
My theory is that he is ok in the 15g, because he grazes along the rocks and sand and the sump pumps in ~250 gph of refugium water (post-skimmer) and replenishes the pods. I also have a ton of chaeto from my sump/refugium that I sort of let sit around in the 15g frag/critter tank. The flow is super low and it just looks like a refugium. I think the fact that I don't clean it at all and leave chaeto floating around helps with the pods.
I think if it was a standalone 15g and not connected to the 30 gallon sump and 90 gallon display tank, the red Mandarin, Manny wouldn't be able to survive. Here is the setup and a closeup of the 15 frag/goby pistol/dragonet messy tank. Its almost impossible to get a photo of the red mandarin because he is always zipping around the rocks. Poop. I'd love to see him more out in the open, but he has a shy personality.
Wow.
Lets not go here and judge other peoples passion level. I understand you think you consider yourself partially successful on the 3rd year, and I congratulate your opinion of yourself. But let's not judge anyone else who could potentially become an expert at the 1st year. We can judge equipment, fish and reefing methods, but don't judge other people.