uhhh, dude, it depends on your roster. you gotta list your team and let us know who you'd be willing to risk losing via the waiverwire. not to menton i don't know what your league's scoring is, and if it favors RBs or WRs or whatnot.
thanks for responding to my thread, and with the link to this in there i'll be sure to check back and give you a thorough opinion... but as a rule of thumb, if you have an expendable roster spot and there's any question that your RB1, very likely the first pick in the draft, isn't going to play.... well dude, short of a situation where you have a sufficient option on the bench to recoup points from AP (again, this is why you gotta list your team's roster), which i'm assuming you're not since it seems like you'd HAVE to get gerhart if AP doesn't play (and again, if you've got an andre ellington or some other bench option and you're asking if it's worth getting gerhart in place of that option, well, that matters)
so basically, without any information to work with here, i'd say that obviously if you're in a position where AP doesnt play and you dont have anyone on the bench to take over his role, then you HAVE to get that backup cuz you don't want to have a dead 0.0 (, mr. blutarski) slot in your team... but if you have other options and you're asking if gerhart is superior to them, well, then i do not know.