Is there a reason that Maw of Chaos opens a portal to the Abyss explicitly? I get that it's from an Adventure Path, so it may fit into the theme, but it doesn't have any [evil] descriptor. Wouldn't it make more sense to say the spell opens a hole to Limbo or some such? I'm not sure how my CG sorcerer would feel about opening a gate to hell, essentially.
Oh a reprinted Maw of Chaos Spell? Neat! That was my favorite nuke spell from D&D 3.5
The Pathfinder version here looks pretty fun, but being duration concentration and the fact that it has no effect until the start of your next turn is a pretty big downside, imo.