I have been using K&N for years as I believe they do offer less air restriction. However, More recently I have been using one in a business vehicle where I travel over 200 miles per day and found after a year or so I was having trouble with sticky throttles which required cleaning all the time. I can only assume that the oily air from the filter causes more of a build up of air particles on the throttle body. Another business vehicle of mine that is driven 100 miles per day using only the paper filter has not had the same problem. Because of this I will not be using a K&N filter for my E when they are produced.
Also, I really cannot see any apparent difference in performance.