The Royal Saudi Air Force operate two BBJ's, the Ministry of Finance have another two operated by NAS. There are none within the Saudia fleet, either royal or special.
Transition to the G2/3/4 F900 fleets is from the MD90 for FO's, or at any stage for Captains upon request of the crew. Older expat Captains have also moved to the corporate side to extend their flying careers.
But this fleet is boring, just think of the career path of the present senior Captains, DC3, Convair, DC9, F27, B737, B707, L1011, B747 Classic then to the newer MD11/747/777.
Mutt.