Why wouldn't one fly an approach like this in FPA mode? Is it that few aircraft have an autopilot FPA mode or that the mode is there but crews are not trained to use it. (MD-11, B-717, and MD-10 all had an FD/AP FPA mode which is ground referenced, not airmass referenced. No need to observe GS and compute required VS. Just dial in FPA -5.4 at the FAF and change it to -3.0 at 5.5 DME. Yes, of course altitude monitoring is still required.)