ahhh...history!
Looking back, I seem to remember that many of the procedures were virtual ILS overlays (due to public outcry on any new procedure)
ATC was complaining that the FAF was at different locations than the FAF on the ILS procedures, and that ATC does not vector to a PFAF (or gs intcp).
From FAA guidance: "If the LOC FAF is defined by a facility such as a LOM, which cannot be moved, the present facility name will be assigned to the ILS PFAF. The RNAV FAF will be colocated with the ILS PFAF and share the common name. "
If that fails!
An underlying assumption of is that the ILS glidepath angle/TCH will coincide with the RNAV VDA/TCH. If this can't be done, a RNAV procedure, completely independent of the ILS procedure, will be developed."