In case anybody hasn't read it, here's an excellent article on the PCV system in general. click
Under the normal configuration, when the IM is under vacuum, air is drawn in from the intake snorkel through the left facing port, through the valve cover, and into the IM through the PCV valve. This steady flow of fresh, metered air, keeps the crank case well ventilated. It also explains why PCV systems can affect idle stability, because the air flowing through the PCV is in addition to the BISC and ISC, so changes to the PCV must be compensated with changes to the BISC setting. And, as we know, under boost, the PCV closes and the flow direction reverses, so that blow-by is expelled into the pre-turbo intake and ingested through the engine. This is where your catch can or oil-separator come in, to collect oil during flow reversal under boost.
Depending on the application, an alternative configuration might be a good idea, but in general there are two problems with eliminating the IM vacuum source. First, the vacuum in the pre-turbo intake track is relatively weak compared to the IM, so you don't get nearly as much suction under normal driving conditions. And second, the VC is no longer 'ventilated', in the sense that there's no fresh air being drawn in. The slight vacuum from the pre-turbo inlet will relieve any pressure built up from blow-by, but there's no way for fresh air to get into the crank-case. As such, this configuration is good for relieving high crank-case pressures caused during heavy load, but generally does a poor job of keeping the oil clear of steadily accumulating hydrocarbons and other combustion byproducts. Hence why it is recommended for 'race-only' applications where you change the oil often and spend relatively little time under 'normal operating conditions'.