Yeah, I'm not sure Thiel's would typically need such large cases for cross-overs, except perhaps for the CS5's. Perhaps something that resembled typical components might be found more acceptable to some?
If external cross-overs were to be considered perhaps both pre and post cross-over amplification could be considered too?
I am most curious about upgrades for the 3.5's! There are a few different things that could be done with that model.