i remember several years ago people all considered crusting monti's to be the most difficult sps to keep......and they had to blasted by light and flow in order to keep them.
now people are saying to keep the superman and sunset milli's low in the tank. and they do seem to do better in lower light with decent flow. my undata and setosa also seem to look better and grow faster lower in the tank instead of being blasted up at the top with my acros.
only encrusting monti that seemed to do well by being blasted was my purple haze, but it looks the same and grows the same pace now that its lower in my tank.
my rainbow never did well where it was at, which was pretty high light if i remember.