I've been using Cerberus for almost a year on 5 phones, and the one time I used it to locate a phone, it was my son's phone, and it was still in our own house.
For my phone, it's also rarely out of my sight, but I did use Cerberus for it once. I was using Secure Settings along with Tasker to lock my phone under certain conditions, and after an update I was unable to unlock my phone - it wouldn't accept the unlock code. After a few minutes of head scratching I remembered that I could unlock it remotely using Cerberus. Problem solved!