Dude I will maybe one day do a harem, but honestly anything is still speculation at this point as "long term success" is measured differently by different people.
The problem I personally see with home harems is what happens when aggression hits? I know they said they moved one because his face was too orange, they had to move a few others because of various things. Any disturbance in the force and they start fighting.
For some reason I always had 12 as a number in my head, but not going to lie, if I raised a clutch of 25 fry then I would have 25 babies. There's definitely some merit to spreading the aggression out over multiple members, so I understand keeping more and would probably myself go somewhere in the 15-18 range.
Clown Harems are still a crap shoot at this point. We have definitive proof they can work in the short term (2-3 years), what we're still missing is the long term (5-10+) years. Many older reefers have clowns in their teens and 20s. Could a captive harem survive that long? I'm not sure we have a definitive answer on that in a typical "home sized" environment.
Just some food for thought and ramblings. HTH.