Seriously though, unless you have stuff on there you are epic paranoid about (in which case a data "shredder" should be used), quick formatting should be fine.
Interestingly NTFS full format indeed only is quick format + block verify, that is it doesn't actually erase the data.
You need to use zero-fill tool for that effect.
In fact I never even considered this would be the case until mongo brought it up couple of messages ago.