I have the same item in my amazon wish list. The only thing (other than SWMBO's approval on expenditures) that I didn't like was the connectors aren't locking. I would really prefer that the control panel be locked in. That said, I have been considering the same cord but hard-wiring it to the control panel so the the only loose connection is at the 50A plug. My planned stand would be mobile and disconnected from power when not in use as I usually brew on the patio and the nearest power is in the garage, so I'd need to unplug to close the man-door to the garage.
I guess what I'm saying is I see a potential safety issue with the plug, but realistically probably not something to worry about. And as 6/4 wire runs about $4/ft at HD, it's like getting a free connector/plug as long as your panel will be within 15' of your outlet. I need to do some measurements, but I think I'll be ordering the same cord eventually.
Good luck on the build.