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.
But I think that some of the F80 developments were combined with further DSP refinements and applied to work for Jaguar/Land Rover.