If i needed to decide "mudflaps or not". Today would have forced my decision, i had to drive along a half mile stretch of re-surfaced road (gravel) . It was a nightmare, listening to all that gravel hitting, even though i was only doing 15mph. I was also very lucky there was no traffic coming from the opposite direction.
they do rub the paint off but only if they aren't fitted tightly enough and allowed to move and scratch the surface..
I did used to have a set on mine but took them off to clean up when i got new rims and when the roush kit went on they wouldn't fit again and i managed to loose one of them somewhere in my garage????
They looked fine on mine (but they blended easier, what with mine being a superior black cat )and because of the cougar emblem etc on them they were pretty smart and they do a good job in keeping the crap spraying up onto your paintwork
If you fit them properly so that they don't flex against the arch they'll be ok. I used 3m tape between the edges. I also sanded the really sharp edge off the flaps. Considering its plastic, they are razor sharp (to get the correct flush fit)