Leviathan get. Hopefully it was worth the Mythril.
Power Breakdown, not so much? I haven't even started the Elite section of the VII event.
Power Breakdown is a significant step up over Power Break, though there are obviously other mitigation tools that make it less than indispensable. Plus, bosses are apparently going to start resisting break soon.
Also, unlike summons, the orb cost for crafting it is not prohibitive.