The problem with the CCV system is that it has to be calibrated for a certain Hg pressure value to work correctly with the engine. Point in case is the link in the very first post of this thread - to e46 Fanatics. The guy who did the homemade CCV system ended up recognizing quite a few shortcomings of his system. A BMW tech jumped in and mentioned it. In the end one of the MAJOR issues is the fact that the M54 engine is using low tension piston rings. He ended up disacrding the project. His system robbed the engine of low end power and the running values were off. Replaced the OEM CCV and and everything went back to normal. Due to the use of low tension piston rings.
A better design of the CCV system which can be easy serviced - yes. Removing it and replacing with a home brewed system - prolly doesn't work well. Sometimes BMW engineers Do know WTF they're doing.