Sadly I have no idea if it's been reformulated, however I have had 2 samples, I have a vintage bottle and a new bottle.
They have all smelled different at some point in their progression, I have particularly noted that my new bottle now 8 months old has matured in the bottle, mellowed and become more wearable. This is somehting I seem to remember reading some where else too.
It would however be foolish to believe that after all this time it hasn't been reformulated at some stage. Will my new bottle end up the same as my 30 year old Knize, I have no idea, I just regard the as different vintages from the same maker.