I have mixed feelings about this, but mostly negative ... our limited success using the "2-headed QB" approach in the past immediately comes to mind, as does Rutgers more recently, although maybe that was because both of their QBs sucked. On the other hand, Northwestern used this approach successfully against us last year. Also, our offense seems to move the ball best when it got in a rhythm, and I think changing QBs messes with that pace.
If neither QB creates any separation by the PSU game, I think it would be worth playing both. Sometimes QBs perform differently under live fire. It's one thing to stand in the pocket and deliver a pass on a practice field when you're wearing a green jersey and both sides of the ball know the routs and coverages, and quite another when the opposing D is throwing different looks to confuse you, while trying to pound you into the turf in front of 50K screaming fans, and 1 mistake can cost your team the game.