The ROS kinda evolved far beyond what the Alliance was. In the end it was quite a mess, in fact I barely ever fully understood the faction. What I remember is that it used to be Outcast based but wasn't actually Outcast, they shot at the SCRA and sometimes acted as Sirius Police for some odd reason I never understood.
I think from the moment the objectives of a faction do not appear as clear it's bound to collapse like it did. It's a point future official factions should take into account I believe.