The chance of a fatality during EF in a piston single, and associated force landing is 17% (almost 1 in 5) according to the NTSB based on years of data.
This is based upon US pilots only but I think that a chance of a fatality in somewhere like the UK is slightly higher. If pulling the chute lowered that 17% to 16, 15% or even 5% (1 in 20) then it is a no brainer, pull the chute.