I run mine like a Deltec, I set the water level once and use an airtap to control the skimmate when necessary, very consistent skimmer, well built, good materials, good skimmate production.
Pumps are OR clones, supposedly from the same factory. (Hailea)
when removing the cup the drain line bumps the union, not a big deal unless you have limited space in the cabinet.
PVC is metric, the newer models come with enough metric PVC and fittings to plumb it in most situations.
On the RPS-2000 that I have, after restart the air must be primed by blowing in the air intake tube, I believe this is an issue with the pumps having cooling channels through the motor. not the venturi or O-ring as some would have you believe. This is only an issue with the RPS-2000.
Oh yeah, just for the sake of full disclosure, I work for a store that sells these skimmers.