I think teh jury is still out on Arcane Eruption, its an interesting spell, combining some very nice control with ok damage but also with highly flexible energy types and the full out area power of fireball.Upon reflection, I think I no longer like the "class feature spells". Most of them El are far too weak for their class level. Sorcerous burst needed to be a d8. Chaos Bolt needs to be 3d8 +1d8 per level. Arcane Eruption needs to be level 3 or 8d6 starting. Sorcerous vitality should be a class feature that scales with level, and sorcery incarnate should also be a class feature usable prof/day. None of those spells are worth a slot. Maybe if you gave a free cast of each, you'd see them used.
Which is a shame; I like the flavor. Just each of those spells are trumped by something better on the arcane spell list.
Its not a top tier 4th level spell for certain, but it might be a solid mid power for 4th.