Personally, I don't think the Tuba24 is well suited for dance music, it is better for live bands, who don't need the extension, and like the idea of portability. It will match the output of a single high quality 18, with less power required to drive, and less distortion produced. The best you can do from a single horn for dance or DJ, is the Tuba36, because it is designed to be used as a single.
Bass horns couple more efficiently when used in multiples, than DR boxes. The Punisher and the Lab must be used in groups of at least 4 to get the stated response to 40Hz and 30Hz respectively. That is part of their design.
If you like the sound of your Kilomax dual 18 boxes, you might want to stick with them. A single Lab will be about equal, SPL wise, to your dual 18, and based on what you said in earlier posts, I am guessing you would like the sound from the dual 18 better. However put 4 Labs together and it will blow away 8 of your dual 18 boxes in both SPL and LF extension. When you are at this level, your tops will be sorely lacking, and the full potential of the subs wont be realized until you go horn loaded for midbass as well. Listen to a system like this and you will be converted.