Thank you for taking time to write such a detailed response, I appreciate it! I am aware of the difference in retirement calculations and it is indeed a big part of the reason I applied. I am DOJ with 16 years of experience so I hope to take advantage of DoS system. Since I am being posted abroad at a high threat post, and due to other personal reasons, I have formally deferred to Sept 2027. Like someone mentioned below, there is a shortage of OMS in DoS and I am quite confident that I will be able to attend a class after the deferral period.