So, what does the over provisioning do that would not normally happen? Some of the drives including some of the Samsung drives state more than one capacity. More often than not it is NOT because they are stating formatted and unformatted storage but because the drive already has space set aside for over provisioning. (note that I use some of the Intel drives as well and their utility is very good but imo not = to the Magician in options)
If a drive, (assuming current generation drive, chipset and Win 7 or 8), formats out to a given amount of space and the firmware detects a bad cell it will take that cell out of service and reduce the space available. The over provision function reduces the space available from the start by setting aside the cells to put into service if it detects a bad cell which ends up not reducing the available storage space.
I have been selling quite a few SSD drives recently and so far have not had any issues with bad cells on any of them and have quit using the over provision feature. The Samsung EVO drive (80% of the SSD drives I sell/use has a 3 year warranty, the other 20% or so I use are the Pro series that have a 5 year warranty and though they are indeed faster drives they are also considerably more expensive.
My suspicion is that with or without the over provision enabled the drive will likely outlast the system.