The oem filter on my suzuki is very high quality, with paper and cotton batting.I had problems with driveability with it (though it is an old carb'd bike), took it off and replaced with stock oem. In general, I have found that oem air and oil filters are always top notch.
KN really does let more dirt in, that is a fact. I have yet to see a dyno here showing the addition of a KN resulted in more rear wheel hp.If the KN really does allow more air in, how will it benefit the bike? It isn't like it has an O2 sensor that will add more fuel to compensate.