One thing I wonder, and since you're using it often you can help:
1. Do you let the Fire Elemental attack, or do you let it buff?
2. What about fights like Elegon and Wind Lord?
Well to answer the first part as a few have probably mentioned you use the elemental to attack. You need to do some crazy amount of dps for the buff to be better than his attacks.
H Elegon is actually were I first started messing around with PE due to buff mechanics. Any fight were you need nice burst I've found PE can't be beat imo. So I just figured I'd try H Windlord with it and liked my results. Besides the Primal Elementals just look plain badass lol.