A-cat is excellent at what it is intended to be. A high performance uncompromising racing machine. You don't want your kids near it and you don't want your kids sailing it.
Apart from that, I'm not to sure that putting the A-cat platform on the roof of your car is something you want to do by yourself in any decent wind. Big surface area and very low weight. But more importantly how do Police officiers in the USA look upon a 30 ft mast protruding out the back and front by ohhh 7 feet.
Over here that is a sure call to get pulled over and receive the full treatment.
Wouter
Cliff,
Ian Lindhal cartopped his Marstrom on his Suburban for a year, it's doable.
I've taken kids and girlfriends sailing on my A-Class with no problems. Just use good sense. Don't exceed 250-275 lbs of crew weight and don't do it in over 15 knots of wind.
The boats are actually quite strong but you need to recognize they are not Hobie Cats. Treat them with care and you will have no problems.