As far as the difference between Gargos and Eyedol... what personality did Eyedol even really have? Gargos is this ultimate antagonist for Jago, a pathway to extended lore for one of the main characters of KI...
... But iDol is pretty much just a big guy with tacked on moves and a large weapon. There's not much to him that you couldn't give to Tusk, or new characters. (Having Eyedol as the "Shadow Jago" to Tusk would actually be pretty cool, it done right).
The 2 personalities bit could be interesting, but that's basically a stance / state change, which we have a few characters covering already, and probably more to come.
He'd actually be a perfect bonus character for S3, in a way.
Anywho, looking forward to our first look at Golem t'day. And we get to see if Omen has had any big changes in such a small amount of time!