I'm considering upgrading to AIS but I'd like to know how silent it is, especially the Firewall component. I used NIS from 2005-2009 and was very pleased with how unobtrusive it was. It never gave a connection alert for a safe application but did block some bad things. I think the Norton Firewall is excellent in that regard. Norton would also recognize updated versions of things and allow them through without problems. This is very important if you're a gamer and get frequent updates and patches to games and the version numbers or even names of updaters change frequently.
If the avast! firewall is that silent and still effective as well, then I'm interested. If it isn't, and sometimes alerts to connections by safe or changed safe apps, then I'll pass.