I think ComboFix may be dangerous for newbies users however is a good addition.
I just tried combofix for the first time a few days ago. I normally remove infections on my customers machines myself.
But on this one machine none of my tools where finding the rootkit. I knew there was one. Combofix found it, and in turn earned my respect.
While using it, it seems to be totally automated, so it seemed rather safe. So I added it to my toolbox

Why is it any more dangerous than the other cleaners?
Shane