Duramax - the 2.7 has been talked about informally. As the last of the True Thiel designs it is very mature and, unlike other products including the 1.6 and 3.7, XO manufacturer didn't go to China. Thiel made those in-house with traditional Thiel parts best-of-form parts. There are a couple of upgrade opportunities.
1: The midrange has a single 400uF electrolytic feed cap, which Jim would never have done. That cap can be replaced with by 4 @ 100uF high grade electrolytics. Or, I have designed a 100uF CSA 160 volt which will clarify the midrange but take more room than this layout will handle.
2: The tweeter feed has a 15uF + 1uF PP which can be replaced by a CSA or Purity 16uF to good advantage. That by itself would be the largest upgrade and lowest hanging fruit. There are also shunts to common in the tweeter circuit that would benefit in a small way. The 68uF electrolytic up to a CSA and the 1.5uF PP to a PUR.
However, the 2.7 is extremely refined for what it is, so it's way down the list for upgrading. I could get these components with my next CC R&D order, as well as the 2.4 caps that Pieter is asking about.