I wouldn't want any Free Flowing Filter for off-roading. Not with that huge cloud of dust in the air and engines sucking it in like a vacuum cleaner. I would want a more restrictive air filter considering lot's of off-roading is hill climbing at a slow pace and high rpm isn't the norm. Unless it highspeed autocross. No K&N for off-roading!
I do like free flowing air filters for the DD on a family vacation, out on the highway traveling out of state. Set the CC and let the engine breath!
I don't think that free flowing air filters do much if anything all by themselves but, I have done a few tweeks in a couple of vehicles along with a K&N that helped improve the throttle responce and a bit of top end power. Todays computer controlled everything...not much!