I can't speak to the oil filter, but I had a K&N air filter on a previous bike. After 2 years and 10,000 miles I noticed that despite keeping the filter clean and oiled, the walls of the air passage downstream of the filter had a film of fine dirt.
Looking at the wrench doohickey on the filter can, the question comes to mind: "How much filter area am I losing to allow for the height of that wrench thingy". Reduced filter element area increases pressure drop across the filter, while reducing dirt holding capacity and through flow.
K&N filters may indeed be good. I would do a search on oil filter performance data. I know that there is a lot of negative opinion on the construction and performance of FRAM filters, and that this opinion is widespread and goes back as far as the mid 80's. I've never looked into K&N, though.