Drum in hat seems to be a superior option, I believe that was what GM eventually went with across the board. AFAIK the Cadillac up until 1985 (at least) was still using the same style caliper that *some* people (no offense, just doesn't seem to be consistent one way or another) have problems with. The 80's Camaro rear disk calipers have problems breaking the arm that the e-brake cable pulls on, seemed to be just another step on the way to drum in hat.
Since drum in hat is a drum brake, no idea why it would be any more prone to problems than a purely drum brake setup. As far as I can tell, it's what GM is using on their trucks with rear disks. If there were problems with it, or something better, they'd be forced to run whatever worked better. The 25-3500's might still run drums, but the parts stores are selling rear disk rotors for the newer 1500's.