The AR unit is very neat design, a great mounting point method, and a technically good filter. I'll put some pics up after lunch.
If you do buy one, make sure you order the 'drivers side' version, which of course as they are made in the USA is our passenger side, i.e. airbox side of the engine. The 'passenger side' kit is hard to fit and involves relocating the turbo actuator vacuum vessels.
Most other oil catch cans seem to use the cyclonic separation method (like a dyson vacumm cleaner) with a simple gauze filter.
335i engines already have a cyclonic oil breather separator in the cam cover, and the fact that so much oil gets past it just shows how poorly it works.
The AR unit is very much like a compressed air line filter, with a 5 micron filter above a catch bowl for the oil to collect.
Seems to work very well too.