Haven't seen this here yet, so thought I'd share: http://mmqb.si.com/2014/03/19/nfl-free-agency-safety-position-evolution/
Great overall analysis of multiple teams' safety additions and subtractions. Seems to indicate Bethea might be a better fit for our defense than Whitner was. There'll be a lot to be missed in Whitner's physicality, but Bethea promises to be more versatile, a better tackler, less-likely to draw penalties, and every bit as good a mentor to Reid and leader on the defense. As the article argues, it might be safe to assume he'll produce better on the Niners defense than he did in Indianapolis, both because of scheme and because of the overall quality of the guys he's playing with. And this on a smaller contract than Whitner with little guaranteed money on the back end. Oh and he hasn't missed a game since 2007.
I'd look for the Niners to draft another safety in the later rounds to try and develop, but for now it looks like they're set for the next two years.