So far the vote is 4 to 1 in favor of buying a new bike. Thank you for everyone who has posted so far. You really are helping me sort out my thoughts.
I'm already in this Panasonic for far more than it's worth. A few years ago I redid the cockpit with new handlebars and brake levers, and converted it from stem shifting to bar-end (best upgrade I did.) Last year I swapped out the steel wheels for an alloy wheelset. I think the reason I'm having a hard time letting go is because I've put so much work into it already. And when the chain isn't falling off, it really does ride nice.
It's weird how we can get emotionally attacked to inanimate objects. The bike doesn't care if I keep it, sell it, give it away or crush it and sell it for scrap. Yet in some strange way the thought of giving it up makes me feel like I'm betraying it.
But I think you're right in that even if I replace the drivetrain I'm still not getting what I really want. I should probably bite the bullet and buy the new bike. I'm starting to lean more in that direction.
Or maybe I can buy the new bike
and fix up the Panasonic, then get rid of one of my others. Hmmm....