The oil and vapors would deffinitely be hard on any
plastic. From what I see at Mc Master their valve is opened
by air pressure where the US plastic seems to be completely
closed in one direction.
PCV has always seemed very confusing to me, but after
every thing I've read I've got a handle on it now, pretty sure.
In my understanding, other than the obvious emissions regulations,
the only purpose of having a PCV system is to relieve crank case
pressure and thus decrease pumping losses.
The article highlighted on like the first page of this post,
even claims to have gained horsepower with a vacuum pump
system vs. VTA on a chevy V8, I think.
So, in theory, if we stop any boost pressure from making it
past the PCV valve we should decrease pumping losses.
I'll be checking crank case pressures on my motor soon
with and with out a check valve soon. Let you know what I find