So 11A is AD, and MX10 is SAD/DD. I gather you prefer, and have the experience, to lead a team. Why don't you check if you will be doing so at the Ministry? It defers from Ministry to Ministry. When I was an AD I was leading a team of 5, but ADs at another Ministry might still be individual contributor.

That being said, the jump from MX11A to MX10 will not come fast unless you are exemplary and if bosses recognise your efforts. Internal rough guidelines for a promotion is 2Bs - that basically means two years before you can get from MX11A to MX10 EARLIEST. So obviously if the SFA position is MX10, it will shave years off your progression.