I wouldn't say that at all. As I have already posted, it's never happened to me with 5 K-series cars, and I don't know of anyone it's happened to. Also, MGRover improved the gasket in the last year so it is far less likely to happen now.
Best advise is if your HG does fail, make sure the garage replace it with a proper Rover one. Half the problem is dodgy garages using cheap parts. I remember when Watchdog did an article on it in one of their programs and they showed a K-series HG in the studio and it was actually not a proper Rover one they showed!