Am I wrong in thinking that although it requires a vector given to two aircraft vice just one, that in the end it means an overall less maneuver as just one might need to make a significant course change to gain spacing while two aircraft making a small change can get the space they need more quickly?
No you are not wrong. Each situation is different but generally the A/C going no.2 will get the bigger turns (more track miles) and the A/C in front will get the best direct.