I have used them this season on my Rally Spec Focus and I really like them. I have a set of the Racetech 4009 seats.
The only time I noticed them on stage is when I slid into a stump at Sandblast and my head bounced off them.
They do get in the way when I am driving on the street. I have to duck down to look under them to check my blind spot on the drivers side. It also makes in very hard to see over my right shoulder at intersections. But that is more that the co-driver's seat and its head restraints are in the way.
An advantage is that if there is a delay at the rally you lean on them a take a little nap before the stage starts.
If you have a car with a small door opening and you like to sit really close to the steering wheel they can make getting into and out of the car a little more difficult. I do not really have a problem in my focus but it is easy to get into the car nascar style, ie both feet in first.
