The tank is mounted in a tight spot so space is a constraint. I only have a max of 4 inches off the back of my tank.
There is enough surface turbulance that I don't worry about getting good gas transfer but as you say, any skimming is better then none.
I used to have a Red Sea Berlin on my big tank before I changed to the PM bullet and that one drove me nuts. I was constanly fiddling with that thing, one day it would work great and the next it would be plugged up and I had to take it all apart.
Sounds like the Prism might be the same