Thanks for the clarifications and additional information, Marbles!
Your concept for the Cardas Patented Binding Post/Poiema!! combination is interesting. If you have copper or silver coated wire coming from inside the speaker (and want to keep it raw instead of attaching spades), I'm guessing you would want to use Silclear or Walker SST at the junction to prevent/reduce oxidation.
That binding post concept also gives me an idea...
For those that might be looking at externally housed crossovers, why not eliminate the speaker mounted binding post entirely? Basically, you would simply increase the length of the "internal" speaker wire from each driver and pass the excess out of what would be the binding post holes. (I'm guessing that a strain relief device at this location would be a good idea.) The extra length - chosen for your needs - becomes your speaker wire. This still leaves you a binding post at the external crossover, but eliminates the extra post at the speaker that an external crossover would normally require. You could even implement the Marbles/Salk/Schult connection at the external crossover if desired.
The only downside that I can see is that you can't swap speaker cables later. Assuming the use of good wire to begin with, I don't know that this would be an acoustic issue. It would still be an issue if you need a longer length later. If you are prone to constant speaker replacement or just long term thinking, I guess it might also affect resale value.