pwsFWI is now a bit more than a year old and has proven its value : it relates very well to the existing indices and the EFFIS Current Situation viewer. This means that the note : Behavioural testing still under way! will be removed from the pwsFWI page at the end of the European fire season (21 September).
Having said that, I have noticed that some users have reverted to the FWI calculations and graphs as shown by FWIcalc as if that one is better than pwsFWI.