this is a complicated issue. if your safety school is not a good fit, i would say don't go. if it is a good fit, some questions to consider:
1) do you have the resources to wait another year, and the motivation to improve your application dramatically?
2) how important to you is job placement?
i'm in english, where the job prospects are not good no matter what school you come from, and i'm open to working outside the field, at least at this point. given that academia has been the defining orientation of my entire life, it would be difficult to suddenly adopt a different standard and value system without feeling like a failure. this is simply a psychological cost of trying to fulfill my goals. but i'm prepared to defer this problem in order to make sure that i'm comfortable financially, geographically, socially, and academically, in the process giving myself the best chance to finish the phd, rather than simply pursuing the shiniest degree with the best placement prospects.