Rosami - the 3.6 is on my to-do hot-rod list. In fact, I have bought a pair and have created the upgrade schematic and layout. The timing issue summarizes as follows: I began work on this project Spring 2018 when 'New Thiel' closed down its business operations. Much research, preparations and preliminaries have been accomplished since that time. However, I am neither retired nor fully up-to-date in the audio world and considerable reading and interacting have been required.
I am presently building my PowerPoint and CS2.2 upgrades and Beetlemania's 2.4 kit of parts is on its way to him. We will digest what we learn and then I will approach the 3.6 next. I intend to develop and offer through Coherent Source Service an array of products for each product. The least invasive will be fully assembled crossovers which you will install in your cabinets, with local technical help if required.
Your situation illustrates our target customer: someone who loves his classic Thiels and hopes for a significant upgrade path which utilizes his extant, appreciated speakers. It is my considered hope that the upgraded 3.6 will please you very well.