Awesome video, the way I look at it the Sundown was the winner in my book. You're getting 5600 watts out of a 4500 watt amp. The rise was .03 ohms higher, and the voltage drop was .2 volts more? The way I see that is if the electricals were even better (more batteries, the car on, etc) the Sundown would have outperformed the DC in straight output because it seems to be drawing more current. Price point is another factor, I know what I paid for my 4500 but I have no idea what the DC 5k is going for.
In my system, I'm clamping 2600 @ 3.67 ohms with voltage dropping to around 13.2 out of my 4500. More than impressive if you ask me.