You haven't lived until you try to get a good hand brake on a Mk2 Jaguar especially if the auto adjustment is full of crud.
.....or on a modern BMW X5, it is absolutely appalling, good job it's an auto, so it can be left in park with no need to use the handbrake.
Actually, in fairness to the ARP4 rear disc brakes, they do work well as a parking brake, if the handbrake is applied once the brakes are held by the footbrake first. As a little test, I tried to pull away whilst the handbrake was on today, and it it held really well, not to the extent of stalling the engine, but it was certainly on, so, maybe Morgan have a point trying to improve the cable run.