Chakster, Hasn't your journey revealed to you that there are many, many excellent cartridges and that the differences among the many very good sounding cartridges are in terms of nuances that may or may not appeal to any particular listener. That is what I have come to believe; there certainly is no one single Holy Grail of cartridges. The existence of so many very excellent cartridges makes it all the more obvious when you come upon a cartridge that is just plain ordinary or "bad". Those can be readily eliminated from the play list. I also agree that matching of tonearm to cartridge can really make a difference. I could only have come to appreciate that by listening to many different tonearms with many different cartridges, and swapping cartridges among them. In particular, low compliance LOMC cartridges really need high effective mass to sound best. I find high compliance cartridges to be less fussy, in general.
For a few decades, the TP was my only tonearm. Then when I started playing with several different turntables, I began to acquire and to listen to other tonearms. I bought the Reed, which borrows heavily from the TP, and I bought several tonearms with interchangeable headshells only reluctantly, because I was steeped in the propaganda against headshells that was in the air in the late 80s and 90s. Like you, I am now addicted to having several cartridges pre-mounted on several different headshells, so i can swap from one tt/tonearm to another with minimal fuss. Doing that is a very educational experience. With a fine quality headshell, I absolutely hear no degradation associated with the extra contacts in the signal path, so long as I am using a high output MM or MI cartridge. With an LOMC, I cannot swear that it doesn't make a difference, but I have stopped worrying about it. My Koetsu sounds its best in my FR64S, regardless of the fact that I must use a removable headshell with that set-up. Also, rigidity of the connection between tonearm and headshell matters much less with high compliance cartridges, because those don't put much energy back into the headshell/arm wand. With low compliance LOMC cartridges, there is a case to be made, I guess.