How many of the installations are professionally designed/tested? If people
are just bolting these devices on with no idea what will really happen
should the worst happen and they are forced to deploy, are they really
offering any safety advantage?

If the BRS is just going to pull free, damaging the airframe, maybe a pilot
would be better off with a parachute and letting the aircraft fare for
itself.

I'm sure these issues have come up before, was there any resolution?