I have used various firewalls over the years including ZA, Sygate and Comodo. All gave some minor access problems to sites at one time or another.
I am currently using Kerio/Sunbelt free firewall for about one month without any problem. I also like the way Kerio advises that one program is attempting to open another. Keeps one in touch with what the computer software is doing behind your back.
As you are no doubt aware, the free version lasts for about 28 days before running in restricted mode. My trial version went into restrict mode after about 7 days.
In conclusion, despite this restriction, at the moment I am more than pleased with Kerio. If it stays like this, I may even dig into my pockets and contribute to their cause.