I find it totally depends. Sometimes it really works well, sometimes not. I wouldn't do cories, but ancistrus spawns are pretty protected.
I'm surprised this one worked, though, because the Pelvicachromis in this tank seem to prefer the pleco caves over their coconut huts. Also, I've had breeding success come to a complete halt when one fish decides that it wants to use someone else's cave for spawning...everything can be fine for months and then one day it's not. So then you change it up or move fish around.
I think if you provide enough cover and choices it can work (sometimes).
