Saw one in person in the box this weekend. Hell for stout! I'm anxious to try one myself. My brother in law bought one for his Logan Trailer. I couldn't believe how well-built it was, but it's made by the same factory as the B&W Turnover Ball, which leads that market segment.
Seen one in a past thread on this forum. Guy used it on the Dalton Highway comming from Alaska down to lower United States or Vice versa (anyway he used it on the Dalton HWY, lol) Worked flawlessly he said. 400 bones is kinda high to me, I will stick to straps and wood blocking on the frame, I'm cheap like that,lol.