The Red Sox came into Spring Training with a few question marks, which got exaggerated during their abysmal 2-10 start. The expected "holes" were catcher and possibly shortstop.
Offensively, Saltalamacchia approaches Martin's numbers with far few plate appearances, and has almost the same amount of 'runs created' in Sabermetric parlance.
Salty doesn't have the same "catcher's ERA" as some others, but he also has caught a disproportionate share of John Lackey and Tim Wakefield, which can't be helping his stats.
Suffice it to say, I don't think most Sox fans see catcher as a need right now.