In the case of the CS2.4, Tom Thiel has worked up a one-sided layout for internal installation and a two-sided layout for outboard installation, the latter to save space and enhance the chimney effect for better cooling. As these will be DIY kits (or, I imagine, send your speaker to Coherent Source for the work) there is a good chance we can each go with our preferred installation. The XO parts list will be identical, it’s just a matter of layout and extra connections in the case of outboard. Tom wondered how the community would react to outboard as an option and I think he now has an idea.
Again, the advantages of outboard are isolation from physical and microphonic resonances, improved cooling, and increased options for further cabinet bracing. The advantages of internal installation are reduced upgrade cost (no extra cabinet and connections) and no added box to reduce WAF.