Update:
Got the 968 back from the shop. New clutch with green-stripe pressure plate is AMAZING. Very light and smooth. "Buttery" is an excellent descriptor.
I was having the problem with bad vibration past 4K. I had a new DMF put in as well. The shop found that the balance belt was off by a tooth. No explanation for why - only had a few hundred miles since the replacement in February.
So now I've had the clutch done, new DMF, new motor mounts, belt realigned, cam timing done. End result is that the whole driving experience is an order of magnitude smoother, all the way to redline. I can't emphasize how much nicer it is to drive.
If I really focus on it, I can still feel "vibes" through the clutch at high revs but the vibration is minor. About the same as what I feel through the accelerator pedal at high revs, which I would consider normal.
It was much more than I wanted to spend

- but the end result was worth it.