I have a couple large EuroReefs, a small Vertex, and a small SWC cone.  I find all these skimmers are fussy...not set and forget by any stretch of the imagination.  Mine are all controlled by a baffle so water height is consistent. I find they all perform best in the lowest manufacturer recommended water height.  When they are skimming these are all good skimmers...they just overflow every once in awhile and I can't seem to make a connection to figure out why.  I just clean the cups out every couple days so when they overflow they aren't dumping too much back into the system.  Oh, and I swear at them regularly.  
