Is AddMagMap a replacement of MMO?
No. The main difference is AddMagMap ability to ADD custom objects to the existing MapSend maps. Both MMO and AddMagMap can create new maps from scratch; but only AddMagMap can add new objects to the existing map without necessity to recompile the map. Maps created with MMO can not be joined with the MapSend maps (or can be joined with significant restrictions), while maps created with the AddMagMap are naturally part of the MapSend maps. There are no other programs that can add custom objects to the maps without recompiling the whole map, neither for garmin nor magellan.