While I use all the lenses you mentioned (as well as the FA 43), my FA31 (MIJ) is way sharper and has better color rendition than the DA*16-50. I use the 16-50 for range, but switch to FA31 for portraits (with larger groups).
Originally posted by Driline I just purchased the FA 31 "Made in Japan" version for $750. Now that I have both lenses I can see the need to own both and am glad I do. I really like the versatility and IQ of the 16-50. The colors are great and at 31mm at F5.6 its almost indistinguishable from the FA 31. So both lenses totaled $1,350 used. Good deals can be had at used prices. You just have to be patient.