I will edit the first link. As for your 2nd link, the user realized it is due to his firewall and not due to Avast. In general, the new version of Avast (7.0.1456) has fixed most of the problems, but some users do not reboot after installs, having conflicting software, may have malware, or do not read what they are clicking on installs and get a new browser that they did not expect, etc. Is any new software going to be 100%? No, but close to it...yes. And Avast put out the bug fix with this new version in less than a week.
It is your machine, so it is up to you what you want to do with it. I personally prefer strong AV protection, so that is why I stick with Avast.