I suppose those FJ human delivery systems were no worse than ejecting, but without the big bang. The survival rates from ejections have been very high, even for the older seats without rockets, so in reality a parachute extraction from one of those containers was probably pretty safe.
When I was running a range many years ago the senior pilot had ejected from an F4, following an engine failure (I think) on take-off from a carrier (think it was HMS Eagle). I remember him saying that his first memory was of hanging under the parachute watching his aeroplane sinking. He had no recollection of the ejection at all.