Well, sad to report, I took the bait! I actually purchased the TRON.
Let me say that you are absolutely correct, there comes a time of diminishing returns. But I have pretty much decided with the exception of a streamer this will be my last major purchase (barring any cable upgrades; not even components because I'm very happy thus far with what I have). See how I tried to justify that? :)
I just received the Black Cat TRONS on Monday so I'm running them 24 hours a day at this point. But my initial impressions are very favorable!
If I had to put a percentage on the differences between the Silverstar 75 MkII and the Digit 75, I'd say the SS is 30% of what the TRON is, and the Digit 75 is 70% of what the TRON is!
The price/benefit ration would place the Digit 75 as the better "value" (around $700/meter) compared to the TRON ($1,999/meter).
But so far in my uber early evaluation with about 60 hours of burn-in time, the TRON is superior. It just is.
Just quickly, the first day I was a tad disappointed because while the depth and soundstage were there, it wasn't as articulate as I thought it would be (a tad bit muddy sounding). So I change the direction of the cable and "Voila!" what I was looking for was slowly coming to life. But there was a certain bright sheen to the highs I was not liking. After 3 days, that sheen is lessening and I can hear better depth to the soundstage already! And it seems each day there's better tonal cohesiveness.
I'll give it a few more weeks and report back! I don't see a lot of in-depth postings about the TRON on here and hopefully, I can help someone else who is in the market for it better decide!