Please correct me if I'm understanding your post incorrectly. Air goes out of the breather and not into the valve cover, so unmetered air isn't an issue.
One issue I had with a breather was caught on video during a dyno run, the amount of air exiting the breather was such that it made the breather want to pop out. I ended up with a small amount of breather oil and engine oil being sprayed out all over the engine/ engine bay but only when the engine was under boost.
The cure? Installing a remote breather reservoir and is installed behind the drivers side fog lamp. When ever I do an oil change, I open up the valve to let any moisture/oil out of the reservoir.
Depending on the amount of boost, you may not want to install a breather tank. Lower boost means less oil spray coming out of the valve cover breather. Sean Hyland had the same issue on one of his mod motor cars. He made an air/oil separator which installs on the valve cover. Its effective but doesn't solve the problem, same for the water filters used in air tank lines. Seems the breather tank solved the problem 100%.
I really like the catch installed on the drivers side of your engine. Nice unit and by design its easy to tell it separates oil/air very well. But does it really?? Air under pressure makes it easy for oil mist to get past the catch and into your engine.
If it is as effective as you want it to be, why not run one similar to that on the passenger side? You can keep the stock line direction and not worry about emissions but still keep the air/oil separated.
One question remains, how will an open air breather affect your emissions? You live in Cali? It's easy to remove the breather and return your stock set up before emission testing.
