Can you point to a single person who has ever served prison time because they
ran an exit node? The government generally needs more than an IP address to
convict somebody of downloading illegal pornographic images. They may not
need that to raid a persons house however.
So the risk is that law enforcement performs a raid on your premises and you
lose your computers, are humiliated by being seen as a xyz criminal, and have
your privacy/papers tossed and invaded.
If your largely clean legally that is (not taking drugs illegally,
downloading illegal pornographic materials yourself, in the possession of
weapons, or involved in other illegal activity, etc).
Law enforcement can probably charge you with crimed unrelated to the search
even if the search itself turns out to be illegal.
What that basically means is don't be an exit node if your not always a law
abiding individual, can't afford/handle a little undesirable publicity during
the initial raid should one ever occur, etc.
Keep in mind most exit node operators will never be raided. If you setup the
exit node properly there is little real risk. There may be from time to time
DMCA take down requests and similar that you'll need to respond to because
your ISP/the DMCA issuers doesn't understand Tor.
