They aren't bad for a hang on back skimmer, I found mine a bit on the noisy side compared to a skimmer under the stand in a sump... but that is par for the course with that arrangement.
I have a lightly used one from my 55 gallon tank - if you're interested, I'd sell it to you at a good price, I have the overflow box too and never used it. You'd just need to get a powerhead for it.