Which pump do you have on it? I have the Rio on mine (yes, I know it will die at some point) and didn't make any modifications to the skimmer itself. I have an overflow from the tank skimming water from the surface directly into the skimmer, which sits in the sump. I have a ball valve on the feed so I can adjust the flow of water to get the right amount of flow. The main issue I have is that I have to adjust the water flow both there and with the 2 output dials (which control how fast the water leaves the skimmer) fairly often to make sure it's not skimming too much or too little. Too far in either direction results in weak skimmate or no skimmate. Easy enough to check everyday when I add makeup water and feed the delinquents..er..."clowns".
I haven't had a Euro, so I can't compare the AM to one. Maybe it would skim 4 cups a day compared to what I get with mine. The Aqua C skimmer I have on my 20 seems to create slightly thicker skimmate by comparison but the AM certainly outperforms the Prizm skimmer I had on my 29 (which also did an OK job for its task). My water quality is where it should be, which is really how I judge the value of a skimmer. Then again, my bioload is fairly low and I have corals that aren't real finicky.