Perhaps 8% is a reasonable number to not lose your digits. Unfortunately, the customer isn't going to be able to decide (unless they buy SawStop's own) until Delta et al. license. and/or significant public pressure is brought (e.g. someone famous losing their fingers woodworking)

Another reason why companies like Delta et al. are resistant to the innovation is the imminent threat of tens of millions of damages in retroactive lawsuits (e.g. by licensing this technology now - it is tantamount to admission that they were negligent in not providing it earlier [at least in the years since SawStop was announced to the industry].

720k * 40% * (2009 - 2003) is a lot of potential class-action litigants. 2003 is the year when Stephen Gass stepped up his negotiations by approaching the U.S. Consumer Product Safety Commission about a federal mandate.

"Woodworking equipment produces approximately 720,000 injuries per year often causing severe psychologic and functional impairment. Responses from 1000 injured woodworkers to a demographic survey revealed that 60.5% of injuries occurred to amateur woodworkers; 42% of injuries were caused by the table saw and 37% of respondents reported amputation of one or more digits. The most significant causal factor reported was failure to use properly installed guards, but personal factors, such as fatigue and postprandial somnolence were also implicated. Twenty-seven percent of respondents required hospitalization for an average of 3.7 days, and 22.8% were treated by hand surgeons."

http://www.ncbi.nlm.nih.gov/pubmed/3498745