You could be right about it affecting certain applications.
Today I managed to speak to a guy who works for the same company as me who I know fitted a replacement K&N filter to his 530i which he bought new 6 months ago. He says he's not had any problems so far but also hasn't noticed any benefits either!
I presume the MAF fitted to his car will be the same as that fitted to my E46 330i which ran without problems.
Clearly it pays to err on the side of caution here. Staying with OEM parts is often the safest thing to do. However MAF failures have been fairly common here in the UK with the standard OEM filter fitted particularly on diesels so I'm not sure what's going on!
E90 320d SE, Steptronic, Sports suspension, 158s, poplar, Anthracite/cloth leather, Jet Black