I've always been a bit dubious about these and came across this (http://home.roadrunner.com/~jbplock/ISO5011/SPICER.htm)today. No idea who the people are who did it but it does seem fairly comprehensive. They do date back a while.
The bits that sprang to attention were the amount of dust passed by the K&N.
However there is no mention that I can see of whether the K&N was correctly oiled.
Ian
You'll always get War and Piece on aftermarket filters,if I lived in in the desert maybe I'd think otherwise but I don't and I've had a K+N in every bike I've owned since the mid eighties,the only exception has been my my K1200 which I have a DNA in it.
I'm at the point now with the fact their so cheap I don't even clean e'm,there 28 quid from a B'ham outlet,but I've got my old K+N if you want it,just needs cleaning,you've got an IOU on me anyway!!
Yes you're probably right that in our damp climate they're not that important. TBH I don't change them as often as recommended either on the Tiger or in the car.
And the "filter" on the A10 won't stop anything smaller than a medium sized bouler....