Good Lord in Heaven, I'm siding with Araysar.
I think the evidence suggests that all option quarterbacks will eventually get knocked out for significant time, and that you are wagering whether their running performance will outweigh the time they're out of the lineup.
It's one thing to be hit in the pocket, when you have 5+ guys deployed to protect the QB, and defenders are coming at you from mostly a, say, 210 degree arc in front of you. It's another thing to be hit in the open field, with guys coming from all directions. (Whether or not those hits are liable to be more violent (the QB is also moving, more likely to have a leg or arm extended before the hit, etc.), I'm less sure of.)
Hell, what's the position with the shortest lifespan on the field? Now you want to turn the QB into that part time, and you don't think there will be any durability issues as a result?
Maybe Kaep is the one guy with the peripheral vision to avoid guys from the side. Maybe he's the one guy who won't slow down with time, who won't be caught from behind. But I sure wouldn't bet on it, much less assume that's the case.
Edit: Yes, the 49ers should be a favorite in the NFC. Hell, they should probably be THE favorite, it it wasn't for the other teams in their division. I'd enjoy this year and be more worried about the 2014 season, as it looks like contracts will be an issue.)