If the Pet provides the main source of damage there while the Summoner provides support Dot then we have a higher up time the we do know. Now when the Summoner dies Dots fall off and the Pet disappears bringing our damage to zero while if the main source of damage comes from the Pet while the Summoner provides support damage, buffs and Pet skill rotations then if the Pet dies Summoner's can still let the dots tick while Re Summoning the Pet or swiftcast Summon if its up.

As for the visual appearance of the Pets everyone will jump at the chance to change there Pets appearance I would imagine modders will be able to make money off of players that want to change the Egis appearance so why doesn't square just change the appearance of the Egi and be done with it.