Tom - I admire your deep-end solutions. I bet they sound good!
For my part, finding cost-effective upgrades that fit the general (albeit stretched) value proposition of Thiel Audio has landed me on Mills 12 watt audio resistors, quite good for $5.
I agree about removing the XO from the enclosure. Not only is there head-banging, there's gradually rising ambient temperature and proximity to driver magnetic fields. The CS2.4 got the XOs pretty far from the drivers, but better is better. I have two forms of exterior mounting. Full-blown is a separate cabinet about 2' behind the speaker that facilitates air-flow and allows more space between circuits. The first-tier upgrade puts the XO on the back of the cabinet. With vibrational isolation tech, we get pretty far along that road. We also get airflow and spread opportunities. I'm pleased with the improvements over stock - especially when the music gets dense, loud or long - the presentation stays much cleaner and more relaxed.