Yeah, I can agree that there is a lot of switching sides in Syria, considering the amount of chaos there(amount of organizations in Syria, which differ mostly in the interpretation of same thing). However, I would rather say that there is more of taking up situational alliances against a common enemy as the situation changes rather than switching sides. What I mean is that ISIS members remain ISIS members no matter the organization they cooperate with. That is what I presume though.
But regarding the matter of ISIS itself, I don't think that "modarate" is applicable to ISIS. As far as I presume ISIS is an embodiment of uncompromising Islam. Besides, the word "jihadist" acquired quaite a sinister connotation in the recent years despite it's original meaning. Though even the original meaning is that of a struggling for smth, but in my understanding the word "modarate" simply excludes the struggle or fighting. Moreover, ISIS in it's very core is an exclusive organization to everything they consider non-true-islam. This means that anyone who joined ISIS willingly can't be moderate by the definition.