Hello Ton1313-
I have done the upgrade AND replaced the stock tubes with others. I have tried NOS Westinghouse, Mullards and Teles. I have decided that my Amperex goldpins sound best. Now to answer your question, in hindsight, I would not have made the investment in the upgrade. Yes, it is an improvement, but the ROI is zero. Given the opportunity, I would sell the CALs and look at a Metronome, Electrocompaniet or Resolution player instead. IMHO, all of these sound better than the CAL.
I have done the upgrade AND replaced the stock tubes with others. I have tried NOS Westinghouse, Mullards and Teles. I have decided that my Amperex goldpins sound best. Now to answer your question, in hindsight, I would not have made the investment in the upgrade. Yes, it is an improvement, but the ROI is zero. Given the opportunity, I would sell the CALs and look at a Metronome, Electrocompaniet or Resolution player instead. IMHO, all of these sound better than the CAL.