A little while back I looked through the NTSB databases on forced landings for LongEZs and VariEze's. It appeared that any forced landing onto unimproved terrain had a good chance of killing the occupants. Alas, I don't recall the percentage. Slower-stalling aircraft like STOL taildraggers, had a much better safety record, unsurprisingly. I'm assuming, of course, that there haven't been lots of unreported LongEZ forced landings.
I'd be interested to see more figures regarding stall speed and forced landing survivability, and I'd have thought it would help in deciding when to pull the handle.