This is not accurate and is a really, really bad idea. It's a fire waiting to happen.
No it's not. This is common practice. As I understand it, this guy is talking about a trailer battery, not a parallel dual-setup in a vehicle.
Go to ANY store and buy a piece of 7-conductor trailer wire. What size is the battery wire? 10ga.
Want to tell me how this is more of a fire hazard than two 4/0 cables on either side of a 1/4" spade connector in a 7-pin trailer connector? Or are you talking about reinventing the wheel in exposexual fashion with a custom heavy duty connector rated at 300 amps?
People have been hooking up trucks and trailers with batteries for a long time, and 10ga is the standard.
Not to mention... you fuse the 10ga lead at like 20A. So where is the fire hazard?
Having lots of luck with the power wire from JL Audio company for my electrical projects. Their wire is probably better than I need but since I really only want to do this wire work once, I figured why not just get the best I could find the first time. Using some of their battery connectors too which have been a big help. Regardless of what you choose, I hope you find exactly what you need for your project.
If it makes you happy to spend extra money on that stuff great. But there is no technical reason it's better.