Hey Stephen,
I'm a relatively new operator, and I run over a half dozen Reduced Exit relays and a few middle relays.
Abuse complaints shouldn't be common coming from IRC - the main culprits for complaints are DMCA and related for alleged IP (Intellectual Property) theft. That would be your torrents and other downloading services. The Reduced Exit Policy disables the ports traditionally used by those services. (But its rude to download off Tor anyway.......)
But remember, a "Very Safe" exit policy is also a very restrictive policy. You may unintentionally inhibit legal activities/dissent/communication/free flow of knowledge.
Also, regarding whether it's a reduced exit, or full blown wide open: It is most definitely strongly encouraged, and sensible to put up a tor exit notice. IMHO get this setup before you open your ports. Define the intention before you implement the decision. There are template notices available that only need minor modifications.
As well, it's always good to contact your provider and let them know that you're running a Tor relay. I contacted mine, let them know what I was intending to do, how many I was planning on setting up, and I specifically asked for them to contact me immediately over any concern. They were more than kind, and understanding. This sets up a positive environment for when they may in the future get some complaints - they will already know it's not YOU per se, and that no malice was intended. Even if your provider says they permit it, let them know anyway.
The whole matter of whether or not the companies that file the complaints have a legal leg to stand on, depending on country, is well beyond the scope of this email. But it is VERY important to understand your rights and responsibilities regarding retransmission of data, as well as that of your provider. In many cases, country dependant, your provider cannot be held liable for retransmission, nor can you. I would STRONGLY encourage you to read as much as possible about this as possible before running an exit relay of any type.
Again, I'm relatively new so others could slam my comments as ignorant or whatever... There is a ton of information available to you. If you're concerned about running an exit relay, I would suggest getting confident (and damn proud) of running a middle relay first, then when comfortable move toward a Reduced Exit policy.
Kind regards,
Matt Speak Freely