As I've said before, the crankcase ventilation system on the UCE 500's is excellent and, IMO, it does not need a crankcase ventilator added to the vent hose.
As for the 500cc piston blowing out a lot of air goes, that is very true with the Iron Barrel and the AVL's which both have very small volume crankcases under the piston.
There isn't a lot of room for the air to escape to so some rather radical pressure pulses exist in the area.
The UCE on the other hand does not have a small volume crankcase under the piston.
It's volume is quite large.
The engine uses the transmission cavity and both side cases, the volume of the push rod tunnel and rocker arm covers as well as the oil sump volume to spread the pressures caused by the descending piston.
When the engine is running, yes, some air comes out of the crankcase/transmission/side cases/oil sump area thru the vent hose but it soon becomes a stabilized, rapidly pulsating pressure.
It isn't like the entire volume of the cylinder was actually exiting and re-entering the crankcase with every stroke of the piston.
After this stabilization of the air pressure is reached, the only gasses that escape thru the vent hose are those that blow past the piston rings.