It's almost unnoticeable the difference between Starfire protocol and heart of Praxic Fire... Plus I'd rather have 100% intellect and use my super more often (weather it's void walker or sunsinger) than 100% discipline. As well Starfire Protocol lets you hold an extra fusion grenade, so you can either use Angel of Light, or the thing that lets you start everything on fire. If Heart of Praxic Fire is 20/20 Starfire Protocol is 22/20... Check it out on my 30 warlock.