Welcome NSQRD, very different user id.
For K&N, I have two experience to share from my Mustang for road and Pajero for offroad.
There is a noticeable shift in throttle response (free flow) you will feel after the upgrade, in my opinion, air filter upgrade is not for additional 5-10 hp, but for quick delivery of existing hp that your car has. This does make you feel the car is more responsive and crisp in throttle response.
For road use, I will highly recommend K&N and better if you can get cone replacement for cold air intake, that practically makes a good difference. If you can't then upgrade a standard OEM with box replacement K&N is also worth the money.
For offroad use, as much as I love K&N but I hate its extensive maintenance to clean air dry and oil almost every month after 3-4 offroad sand drives. So now I keep the OEM for every week playing and switch to K&N if I'm heading to some extreme areas for long hill climb to get a better quick response.
For buying you can compare local price with K&N website, as I found their website was cheaper including the shipping and package came in 3 days times with FedEx. This also made me tension free that I'm buying an original one and not replica's
Last but not least K&N website warranty is awesome, I broke my Pajero filter and send them a few pictures on email and they send me the new one without asking anything within 3 days with FedEx without even shipping charges.