I love the idea of having automatic officer promotions based on the number of jobs available at each rank. The existing ratios would have to change in C# Aurora anyway as there will be more requirement for junior officers now without increasing the senior officer billets, so unless the ratios can be altered per rank then basing it on available billets makes more sense.
Another thing I would suggest would be allowing officers not assigned to a ship to only advance their political influence... That way if you have a lot of unemployed officers, your senior ranks will get dominated by the right sort of chap with the right school tie, at least until a bit of frontier arithmetic weeds out the more useless...