Just to clarify, my reasoning behind the 0awg is that if you're going to run silly expensive cable, it might as well be big enough for anything, including any curent spikes. How are you guys measuring that you don't need Caps / bigger cables?
Inline ammeter? Voltmeter?
On the more mental systems (especially running into low impedances) I would find cable warmth an issue, running seriously high output the cables would gradually degrade, the voltages would start to creep.