If you’re going to err on one side or the other...to me...over-damping is preferred. At least you’ll have some coherence.
In almost all cases, carpet is good to have. Only time it’s not...is if the room is overly damped...which in most cases is never the problem. In my experience, rooms are typically under-damped.
Best to treat all the frequencies evenly with a balance of diffusion and absorption.