I had always assumed that M80 was a debadged F80 but was otherwise identical (unlike AD88). Iirc It still retained the composite construction which was touted as being key to F80 audio quality but I guess it was debadged due to a limited time cross brand license agreement but allowed Meridian to continue with the construction for a period of time or until it needed to source more/different cases. I wonder if the McLaren tie up had anything to do with it.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).