I used Avast for awhile. It seemed to work Ok, but I found that it has one or two huge (in my opinion) security flaws, mainly that it uses the same password to access (and remove) the app, that you also use when you send txt messages to your phone to activate or use the remote features. It's fairly easy for someone who knows what they are doing, we'll say in the case of your phone being stolen, to put their simm card in your stolen phone, which then notifies you of said act, at which point it is assumed you will txt your phone some kind of command like "lost" or lock or wipe, etc. But in the meanwhile, if the thief puts his simm card back in his phone, and leaves your's off, he should get your attempts to txt your phone free and clear (including your password), at which point he can use it to remove the app and poof that's all folks lol Of course you could argue that the thief would have to know that you have avast installed on your phone to do this, but the nice bright orange avast icon on your pull down bar pretty much assures that. Also these programs kinda scare me, especially avast since it takes advantage of you being rooted. You are basically turning over the whole keys to your house to them, because of the nature of what they do, they have access to pretty much ANYTHING on your phone. And there's been reports that several "phone home" whenever they want, and really, who knows what they are sending?
