Earthsplit is well... one of the crapest Roots in the game. That said however its fantastic for mages.
As a mage you don't use it to part things like most classes would, its thier more of a OH CRAP style root and is perfect for it.
mages do solo very well, however unless you have trouble with aggro I wouldn't recommend the Earth pet in general xping. Earth pet is really for places were you don't have a lot of room to work, and can't have the mob moving. Otherwise our other pets win out. Fire pet is great for DPS if you dont need him to do serious tanking, otherwise the water or air pet would serve you better.
Mage/Necro I think would be a more effective box combo then mage/wizard *shrug*