Went to buy oil filters yesterday and asked for the K&N's. The parts guy at the Suzuki Dealer said that the Suzuki filters are made "right" and the K&N's are not. Not sure why; it doesn't really matter to me one way or t'other. Except that the nut on top of the K&N's is very convenient!
He didn't have the K&N's so I bought the Suzuki branded filters anyway.
Make sure you change out the comptression washer on the drain plug every time.