Up to which level an appraising and valuation officer is going to be promoted after being inducted directly through FPSC?

What's the rationale behind the idea that appraising and valuation officer is more charming than other BS-16 posts including Inspector investigation FIA? These posts were recently up graded to BS-16 from Bs-14 and Bs-15 as I read somewhere. Kindly someone illuminate the future prospects of this job with special reference to inspector FIA. Regards