Many years ago, I use LR for FOT and soon all kind of troubles apear until I added copper to cure the fish while LR became DR (Dead Rock). But I still think DR is pretty for decoration and far more natural than using dead coral. You could cure the LR w/fresh water + copper before using it into the FOT. It save you from troubles. I agreed the 馬氏佈景板 create dead flow zone which is why I gave up mine. I am also thinking to put some DR at the back of my tank and add some 細假件珊瑚 and make it looks like a drop-off of a reef. My only concern is that any dead fish inside it will be difficult to take out!!
Your dwarf angel is nice but I heard that this species is fairy aggressive among it's kind?! That means you can only keep one. Maybe in your gigantic tank can keep a few more pcs without any frighting