I'm a bit gun-shy about messing with the tone of my 2.7s
The upgrade circuit is nearly identical to OEM. “Nearly” in that bypass caps will alter capacitance by about 1%. Otherwise all cap, inductor, and resistor values are unchanged from Jim Thiel’s circuit. The difference is a substantial upgrade in parts quality. Tom Thiel posted earlier that Jim was well aware of the benefits of higher quality parts but made his choices to optimize the performance/price curve and keep his speakers attainable for regular working folks.
But there are audible improvements for those willing to open their wallets some more, especially given the increased performance with time. Many of the parts Tom is planning for the upgrades were simply not available 10-20 years ago. I consider my CS2.4s to have excellent cabinets and, especially, drivers. But there is ample opportunity to upgrade the crossovers and get notably better SQ.
That said, Tom Thiel will be measuring the results of the upgrades to ensure that the balance is not upset in some unpredictable way.