I honestly dont think there is much difference between the 2 brands. We sell both and I cant see any difference. The K&N is usually a little less expensive so I would go with that. You do not have to remap after a filter, but for the most performance I would do it.
If you really want to be happy, don't upgrade because you want more HP. Upgrade to a BMC or K&N because you won't ever have to buy a new air filter. Any added power is just a bonus/images/icons/wink.gif.