> If someone is vaccinated AND still spreading the virus, is it any different from having an asymthomatic case of COVID?

It carries about an order of magnitude lower risk of hospitalization or death, so... yes. Yes, it is very different. We don't know about long term effects, those are, y'know, long term and hard to study in this kind of timeframe. Which is why the linked article is notable.

Also note that risk of transmission is about 10x lower (vs. delta, better vs. the older variants) for the vaccinated. So even if they're just as likely to see long term CNS issues from infection they're vastly less likely to be infected in the first place.

I don't think this article changes the vaccine calculus at all. Get your shot. It's your best protection against everything to do with covid.