I'm not sure what percentage of user IDs you will see passing by. Another concern is however that the majority of the OpenDHT traffic appears to be originating at OVH-hosted nodes, not actual users. These should be able to associate your user ID and IP address.
That's the issue I see here: end-to-end encryption is great, but a setup where any party can start collecting metadata fairly easily probably isn't too privacy-friendly. And the issue is known of course, so devs recommend using VPN or Tor.
Note that with a central server instance one has many of the same concerns - but compromising a server is a bigger hurdle than running a bunch of OpenDHT nodes, and there is also a higher chance that some irregularities will be noticed.
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