Running a Tor node is an all or nothing proposition - either you accept fully
the ramifications of a personal identifier (no matter how flawed it is) being
tied to this subversive activity FOR ALL TIME, or you don't.
You don't need to run a node for your ISP to know that you are a Tor user. Even
downloading Tor is enough to make a person suspect in some places.
I witnessed an incident on the #tor IRC channel in which a user that had decided
to operate a relay was looking for guidance on what kind of relay. Several
people warned against it because of privacy the "privacy risks" involved. (This
wasn't very long ago; maybe there is a log.) I got the feeling that the person
then seriously reconsidered even bothering.
I don't think that running a Tor node is considered a subversive activity in
Democratic nations. I encourage anybody who can run a node to do so if they have
resources to spare.