I have a Nauticam Housing for a D800. It was just completely serviced with all new internal O-Rings by Nauticam. I also had Nauticam add the vacuum system to the housing. It has a 1 week trip of photography since the service.
Jack Connick at Optical Ocean Sales in Washington knows the housing as I do all service through him.
The handles have some scuffing, but that's about all in terms of wear and tear.