[Graham]

Combined positions could theoretically lessen the blow of a good round followed by a really bad one.

It will also give an advantage to a car with a bigger combined time than a car with the same combined place score but a faster combined time.
i.e. 2nd & 3rd with a faster combined time vs 3rd & 2nd with a slower combined time.  In some ways that doesn't seem fair to the car with the faster combined times.

I have realised during this Round that for Rally type stages, if a car has a really bad result due to say "type of guide fitted, braids, or controller settings, or some other obscure unexplainable reason" the time loss can be unproportionately excessive so that on the 2nd round there is little chance of recovery to get a balanced combination result. With a "live" Rally type meeting the owner or driver can do much more to offset or resolve those issues on the day, to mitigate the effects of a poor running car on one stage or another. 

I have spent this afternoon comparing the points allocation to both scenario's based on these actual Round results, and by allocating the points  to both stages seperately had a real "buffering effect" against the diverse effects if combined.