A few numbers about how good the pet will be after you hit 95 and replace your old EM8 Earring with the shiny new EM 11 one.
Air -- 15K HP increase
Earth -- 21K HP increase
Above results came from buffless pet duel with a Bard.
Tanking: EM 11 Earth recieve 13% less damage when fightng Level 90 Mob(Living steel in Argath.
Hope this help.