I've used K&N air filters in my last four new cars and never had a problem with oil affecting the MAF...I think that's merely a myth.
My experience has been a 2mpg improvement in gas mileage on every car I've used them on, that makes a huge different in the long run since I drive 100 miles/day!
In the CX-7 I noticed a new growl to the intake right away when installing the K&N and you can almost here the enging sucking in the air, it sounds awesome! Really a noticeable improvement over the stock filter. You will not notice any real hp gain but the gas mileage is reason enough to buy one.