Class A and Class C problems are the same except Class C motorhomes can develop leaks between the cab and the overhand. Since Class A's don't have overhangs they cant get leaks there. Also I haven't seen a Class C diesel pusher (yet).
And you probably won't see a diesel pusher, either, because the reason there is a Class C is the availablility of the van-type chassis. Which, for me, made my decision for me. The driver/passenger compartment was suited more for driving than the ones we visited in Class A's. In a couple of Class A's, you couldn't even put the driver seat all the way back to drive! There was a wall behind it. By design? I was always disappointed with the driving position on the Class A's. (At least on the ones that I could afford at the time.)