I'm not sure that any of the 58 would have died if they'd used the chute. There have been a number of fatal Cirrus accidents where the parachute couldn't have made a difference - most notably flying into terrain in IMC. But the 58 are the ones which happened in situations where other pilots had pulled the chute, and everyone on board lived.
If you use the parachute high enough - about 400ft in level flight, or 920ft in a spin - and slow enough (demonstrated speed in certifcation was 135kt, but there have been successful deployments at 187kt and only one parachute failure, which occurred at something like 270kt), then you will live.
The Cirrus fatal accident rate was initially slightly worse than the GA average. Recently it has improved significantly - quite probably because more people have been using their parachutes.
The average accident rate, using NTSB data, for GA flying is 1.24 fatal accidents per 100,000 hours of flying. If you limit the selection to personal and business flying (i.e. not flight training), the rate is 2.38 fatal accidents per 100,000 hours. The Cirrus rate is 1.57 over the last 3 years, and 1.07 over the last 12 months. There is lots of data freely available on the COPA website (
www.cirruspilots.org).