Originally Posted by BlastRadius
Gossamer - cold-forged aluminum.
Energy - hollow-forged 6061.
Not sure which is better now but Gossamer used to be higher in the product suite than Energy.
The Gossamers look to be a more svelte crank arm.
This changed recently according to the guys at Reparto Corse. Apparently FSA bumped the Energy up the product line and nobody knew it, so sales weren't great. The new Energy Mega Exo is at a higher price point than the Gossamer, and significantly lighter.
So buyer beware--the super-cheap Energy cranks you find everywhere on clearance are not the ones we're talking about, at least not me or blandin.