I only got 1 abuse complaint, but I also only ran a Tor node for about a month with a reduced exit policy. I explained that I was running a Tor exit node, told them I blocked the offending address, and then linked to the Tor Project website for more info. They thanked me for my time, and marked the problem as resolved.
Interesting enough, the abuse complaint was from Webiron, and was never marked as "resolved" on their website.