BRS has its own problems. I think Marc, et al, have said that safety is a series of hopefully thoughtful tradeoffs. In the case of BRS you need to evaluate the cost of BRS vs something else you could do.
A BRS is minimally going to cost $12K. $12K buys a lot on an aircraft. That money could be used to make you powerplant system more reliable, better flight instruments, additional training; all of which may have a better payoff than BRS.
BRS has additional issues. Like Chrissi pointed out flying at night or over inhospitable terrain is where it shines. However, approach and departures are where a lot of the accidents happen. That means you have to make the decision to deploy very quickly and be reasonably sure that firing that beast off is the right thing to do.
Additionally, BRS is going to add weight, real estate, and CG issues, plus you will be the pioneeer. If the wife really wants BRS it may be a better idea to look at plane already equipped with one.