AOS get's more important in any motorsports application. Extended boost periods also increases the chance of blowby forcing crank case pressures to go up and forcing atomized oil through the system. Oil contains 0 resistance to ignition if ingested through the intake and burned, it effectively lowers the octane level of the fuel, which increases the chance of detonation.

Capturing oil before it goes into the intake is important.

Problem 2 with Boxer engines:

The oil return gallery is below the cylinders and contains no baffles preventing the oil from backwashing into the valve covers. When pulling high G's (greater than 1g) sustained, as in Turn 3 of mosport or Turn 8, oil can and normally does pool in the valve cover and gets forced up the valve cover vents, then into your intake. We use customized baffles in the oil pan to prevent this from occurring.