Some legacy systems cannot even handle TF legs, even if they have been designed as such - and some have been "recoded" as VA legs (by HWL, not the database houses) - that is scary, to say the least. The difference is significant - better to fly the procedure manually.
I have worked extensively with a major Far East airline who cannot fly GPS approaches in Australia as these procedures were not originally designated "RNAV" - a crazy situation.
Many FMS cannot cope with RNAV NPA that do not have the MAPt co-located with the runway threshold.
Anyway I am still convinced that you dont know what you are talking about
As part of my job I am involved in the design of instrument flight procedures - including all RNAV types - i.e GNSS (started 14 yrs ago), RNP to <0.3 with or without baro-VNAV and have worked with ICAO & IATA in moving towards consolidating nav specs into the PBN concept. I also flight validate them & code them. Apart from that, you may be right
