Yellow,
Seems that Delphis own routines are bit flaky. There has been bugs over years. Last problem I had was that TryISO8601ToDate will raise exception on string it can't parse. Will handle/eat the exception but not most optimal solution I think.
By good,m I mean that handle nicely error cases, maybe has more options that Delphi version. Obviously very well tested. If also fast, I wouldn't complain.
-Tee-