My catch can works fine, all it cost me was the 42DD plate and manifold blank as i had a catch can laying around. Not doing so much at the moment, but the amount of oily water condensate it caught during the winter was surprising. Not surprised it doesn't help with the valves, as most of that is caused by oil seeping through the valve seals
It's also one less potential issue with PCV failure or vacuum leaks. Wouldn't recommend a PCV blank as they restrict the passage through the camshaft cover to the rear breather which can cause excessive crankcase pressure
With the catch can setup, it always goes through the catch can, both vacuum and boost, and it all feeds in to the turbo through the rear breather on the camshaft cover.