I use a Phoenix Squad at 7*, G8.X and left Sabine out. They take me through GW all by themself with occasionally some canon fodder squad on 12 before clearing them with Phoenix. They are really good and definately above their league. Though they are getting weaker in Arena, i could easily destroy Squads with more Power than me up until Level 70. Still am on 11 and the main reason not being higher is stronger (or evenly strong) Phoenix Squads, because Phoenix vs. Phoenix is a pain, almost always draw. Same against Ewok Squad. Lacking the Damage i guess cause Ezra is the only real hard hitter.
So yes, get Ezra and push him, in fact he is the most qualified to push above G8 i think.