I would put my pair of Tuba30s up against any box on the planet of equal size, including a single Lab. The only ones that would give it any competetion would probably be someones DIY, I am not sure if Danley has a box that small, but if he does, it would be interesting.
The only standard in "the industry", is not being totally honest about specs, as Mr. Fitzmaurice is. If you have the time and some woodworking skills, they are well worth it, as a lot of people are finding out.
The Tuba36 can be built for less than a Lab, no aluminum plates required, most of the path length and bracing is 1/2"BB, and a wide variety of drivers work well in this design.