Surely if your figures of 20% Likelyhood of death are true with 100% success with the chute the manufacturers are being negligent in detailing and recommending a forced landing?
Please supply a link to the 20% Fatlity rate in forced landings?
I once went through the NTSB database looking at engine failure fatality rates for different types of aircraft. I don't recall the numbers, but if you were flying a Long-EZ your chances of surviving a forced landing off the airport were quite low - less than 50% as I recall. In a Piper cub, the chances of survival were an order of magnitude better, as you would imagine. I would imagine they'd be somewhere in between for a Cirrus.