I was a fairly early adopter of the slippery clutch parts upgrade on pre-slipper clutch bikes. I’ve got 50k miles on the bike now, probably 35k since the clutch upgrade, and I’ve had no problems with it at all.
Initially I liked the lighter clutch lever pull, but now I can’t really remember what the original one felt like. But what I do notice more in comparison to my other bikes is the “feel” of the engagement zone. Not sure I can adequately describe the difference, but it is different, and I like it.
It was a good amount if money. Around $300 for parts when I did it. No idea how that has changed since then. I think it has improved my enjoyment of riding that bike. I guess that is worth $300 over 6 years (and not selling anytime soon). Heck, I spent more than that for YES warranty extension and never used it once.