For you they're useful when you get body to mind skill. You recharge mp and lose hp. Pet heals your hp. So its still very useful.
For a melee is even more useful since the new pets heal. And from what the guide says and some people corrected me :p, with blessed beast spiritshots, they can heal very nicely. They also have battle heal when your really low on hp.
So they are indeed very useful. And they all do the same thing. Heal and eat 10% exp. They just look different.