Never liked the "split" of the comunity in the first place... and never understod it either. IMHO MOS/AROS/AOS/OS4/UAE are all amiga related and will fit in here.
MOS was THE successor for Classic AOS for a long time before OS4 came into the picture. There is a reason lots of great Amiga gurus/developers jumped on MOS in the begining.
Rest is what you say... history