Thanks tebasuna for the confirmation...
During my tests it occurred to me that I could basically build my whole normalization plugin based on FFmpeg. It contains SoX, it can do EBU R128 analyzing, it has DynamicAudioNormalizer built in, and it comes with Loudnorm. But this would mean a total rewrite of my plugin, and frankly I am not up to this...
Cheers
manolito