Gary..I also ran into Sam Leach as he's a part-time promoter of American English, a Beatles impersonation band in Chicago...Great guy..I hear he's not doing too well, now, though...
As for Best, Martin, Lennon/McCartney and Harrison have taken credit for dumping Best...Epstein has been thrown into the mix as the main reason he was ousted...I don't know what to think...
There's a new book or documentary out on Best which you have to take with a grain of salt, but I do think it's possible that Best's popularity could still have been the main and sole reason he was ousted...
Also, in Spitz's book, the potential rift between Best and the other three developed when the Quarry Men (John, Paul, George) left the Casbah because they didn't want to pay Ken Brown his share the night Brown sat out -with Mona's blessing- a show yet Mona gave him his share. Spitz asserts that Best held a grudge against them from that point on and never became one of them.