It's a simple system and it works. It is however a bit limited by the rather torturous route through the cam and rotary valve, and it can be prone to collecting oil which it spits out.
By putting a hose on the outlet and routing it back on the bike you may think you have taken care of these spits, but oil and emulsion will collect in the hose and plug it. This renders the whole system ineffective, as no breathing out occurs. BSA A65 didn't even have a outlet stub, and is all the better for it.
I usually leave the outlet bare and try to find other ways to mitigate the problem. Triumph inserted a short piece of pipe into the inlet hole in the cam on some cams. They idea must have been to let the pipe stick through the layer of oil that wraps itself around the cam as it spins. This phenomenon is well known and is why many engines have scrapers close to the crankshaft.
The extra pipe is another obstruction in the system though, and I don't like them.
I'm thinking that trying to evacuate the oil more efficiently is a good thing, making sure the oil pump works at its best and that the return system is open and to correct dimensions.
On the Triton I'm working on, oil spitting is an issue, and I suspect the restriction in the custom return system is too small. This effs up the system in two ways, residual oil level becomes higher, and the increased back pressure forces more oil through the rockers, and more drain back over the cams.
I like the timed breathers, but the later engines that breathes through the primary are less troublesome in this respect.
One last word on timed breathers; don't ever try to "help" it by adding breather hoses everywhere, unless there's a reed valve or other PCV valve connected to it, or you just sabotage the system.