There are a number of issues here, and some good material is available if one is interested in the subject. The 733/4 is loaded by zone and there is little to be gained by swapping a few people foward/aft except in take-off & landing modes. With the greater flap settings the forward CoG can become critical. Higher landing speeds with less flap will be required when forward limits are exceeded; additinally, with fuel burn considerations, landings into short strips can be interesting. Cruise is therefore not as critical.
Early days in the larger airplanes were also interesting as it was found that an aft CoG was able to provide an extra couple of knots in cruise - all flying elevators gave a little more lift than calculated and the airplane sat up & was quicker than predicted. This was useful in getting better economics when used correctly.
We all remember that while the DC3 had a CoG of 23% MAC they used to fly quicker at 18% - & a couple of knots in this beast was more noticeable than in a modern airplane.