I liked it when our set bonuses actually made chaos bolt better.
T18: Reduces the cast time of your Chaos Bolt by 2.5 sec.
T19: Casting Chaos Bolt reduces the cast time of your next Chaos Bolt by 40% for 4 sec.
T20: Chaos Bolt always gains maximum benefit from your Mastery: Chaotic Energies.
I dont play this spec for portals or demonfire