A few things make me lean towards Cardale being the starter next year. With him not getting nearly as much work as a runner on designed runs, the offense doesn't get too one dimensional relying on one single player like we have seen at times with Braxton. Miller can take over a game for long stretches, especially against inferior opponents, but when he if forced to pass against better competition, at times his teammates seemed out of sync after going unused for so long.
With Cardale they seem much more unpredictable offensively and when you add in his arm strength, where no part of the field is off limits on any given play, it really softens the D up quite a bit. I don't think it's any coincidence that Elliot's two best rushing games came while Cardale was at QB despite it being against probably the two best defenses they've faced.
While there is limited experience, I'd say Cardale also gets that 1 yard when you need it. You won't see him trying to beat a defense to the edge on a 3rd or 4th and 1. He's mashing that bitch right down their throat and probably knocking a mothafucka out that tries to get in his way. Just ask future top 10 pick Landon Collins. http://espn.go.com/video/clip?id=espn:12110021