i had a maxima with 160,000 miles, and i never used anything but a paper OEM style filters(dont know why, just chose not to mess with it).
I went through two MAF's in the course of that mileage simply due to dirt/age/etc. its a common problem, and with higher RPM's = more oil vapor that is pushed back into the intake system that can lead to clogging of the MAF.
i also have a G37s with not one, but TWO K&N filters and over 29,000 and not a single issue.
i also have a 2007 GSXR600 race-bike that see's 16,000RPM (yes i said 16 thousand RPM) at the racetrack for hours, and it too has a k&N and not a single issue.
-and now my Rogue will be getting a K&N filter as well
K&N dipped a MAF into their oil - completely submerged it, and the MAF test to work fine.
i really think the guys that are having problems, are having problems with the MAF itself, and attribute the problem to the K&N making their MAF fail. Or they are revving their engines and the PCV system is not working up to its full potential and ends up re-routing the oily vapors in the area of the MAF and THAT is doing the damages.(just take a look at your filter, does it have black oily residue? thats your crankcase vapors).
thats same problem can come from high revving, worn piston rings, super low viscosity engine oil, or faulty PCV valve, and just normal operation. MAF's sit in a nasty place; and are prone to failing.
I just think the dealerships got work from the manufacturers to not waste money on warranty work and blame the k&N filter.
dont forget, nissan is signed up with AEM filter/intake system