I personally think they're fine, never had a trouble with them before. And I do think they should be conjuration because they do bypass SR...conjuration is about the only school that can regularly bypass it. Think of it as summoning a orb of energy that you're throwing at something, which would be conjuration territory not evocation, which basically just makes stuff go boom. Now Evard's Black Tentacles, thats too powerful in my book for bypassing SR, but that's not what this is about...especially friggin warlocks with it, ooh I squeeze and do cold damage, as often as I want...fly around, litter the battle field with writing tentacles of freezing death, fair fair. Also the fact that they're only close range which means that if the wizard can hit something with it then more then likely whatever its hitting can charge the poor wizard who just got somethings attention. I think they're when compared to other spells at about those levels.
I also don't understand why the lessers do 1d8 up to max of five and the regular orbs do 1d6 up to a maximum of fifteen, except force which is only 10d6 max and sound which is 15d4 max. I personally use the lesser sound because very few things have sonic resistance and its a good spell to finish something quickly.