I use Comodo on and off, when i am not running something else to "test" drive. Have never had an infection with Comodo on my system. I tend to tweak it out some, and still have very little "pop ups". I usually set the "configuration" to Proactive, in the firewall i set it to Block all incoming while stealth ports, "outbound firewall setting is usually "Custom" with the sandbox set to "Restricted". Once I set the rules for the applications out bound, the Suite quiets down. It is extremely light on system resources, especially for those who do not have the power of dual core, or better..
I have run into a couple problems with downloads, especially with the sandbox set to restricted, but after it has been sandboxed, and analyzed, if no problems found, it will download. So all in all, I personally think Comodo is one of the best Suites "especially free" out there.