For everyone's info, Dennis Labs is part of the huge Dennis Publishing Group, originally created by the late great Felix Dennis. One of the Group's titles is "Micromart" magazine, which some UK forumites here may know and read. MM is I believe, the world's only weekly computer magazine. MM also has a forum, with a dedicated following (ahem!) but recently the forum has been down several times, there is speculation whether this is anything to do with the recent death of Felix himself!
I use Bitdefender Total Security and MWB Pro. There is no conflict between the two and both can be set to work in the background, updating and scanning at set times, however they also both spot anything that should not be there and report it. I began with the MWB Free version, which first picked up malware 2 years ago. I purchased the Pro version and was amazed by the amount of garbage it found. I accessed the MWB forum (only in paid for versions) and received great advice, over the course of 2 days I found and removed literally dozens of nasties: toolbars, malware, PUPS and even Trojans.
I have never been without either programme since. They are for me, complementary and each works in a different way to watch for and take care of trouble. I carry out a system scan with BD once a week, and MWB does its "Threat Scan" thing 2 or 3 times a day.
To test any Free programme against a purchased version would seem to be against common sense to me. Check out what is available in any purchased AV and then check out a similar free AV programme, to see what I mean.
I might also add that, at the time my PC suffered an attack, I had been using the AVG paid for Internet Security. It picked up none of the nasties that BD and MWB spotted and killed. Now, before anyone tells me that they use AVG and it works for them: how do you know there is not something lurking in your machine? And it has probably been improved since I used it, the AV was bought up by a larger company I believe.