When Rob Farmer was chasing a mixture problem he fitted a "O2" meter to his RS? which he could read out on the road, and found that the flat filter didnt flow enough at high revs , and stuffed up the mixture.
He fitted a old style round filter which flowed better, and didnt affect the mixture as much at high revs, but it still wasnt perfect.
Last I can recall he was working on modifying a flat filter so it did flow enough.
So he got the opposite result to Plaka.
But I am not saying either is wrong.
Same thing with the snorkel set up - some folks remove them from the flat air boxes and their bikes will hardly run - others get an all round improvement in throttle response and much sweeter running.
So , what is true and undeniable for some folks just doesnt work for others.
I suggest you just try what you want and see what happens.
And if it doesnt work as planned on your bike, try and figure out why - every bike is the sum of its parts and your bike probably has some parts different from other bikes.
Some folks extend the breather hose out to a catch can in behind the battery somewhere, and vent the can through a auto breather filter - from an engineering viewpoint you want as little oil in the combustion chamber as possible anyway.
Adelaide Hills, Australia. 93 R100 GS, 77 R75/7 ,70 BSA B44VS, , 86 R80 G/S PD, 95 BMW Funduro F650 ST