I used lookout from the day I got my phone because I use it for business, process credit card transactions via my phone, and have my business files sync’d via dropbox. I don’t install non-market apps because I’ve yet to find one I needed that badly.

I Stopped using lookout when I started getting serious slow downs and problems with their setup after they moved to the Pro options being locked out. Installed avast the day I saw it on the market- haven’t regretted it one bit, it uses less than 1% of my battery and is an added comfort.

Now that I’ve read multiple reports of marketplace apps containing malware to cost me money - as well as applications that have push banner ads to notifications…I think I’ll trust avast! to warn me of potential threats over waiting till my bill arrives.