It'd be great to wipe the free space ONLY and skip the MFT wipe. The MFT wipe, for me at least, can takes several DAYS to complete. Not sure why, but I'd rather skip this step as in the scenario I'm using it for, it's not very useful in the first place. Why? Virtual machines can be shrunk greatly when unused space is actually zeros, wheras the MFT wipe appears to be some sort of obfuscation pattern only to hide filenames and such. Simple as that, I think.
So, in short: please add ticks for "Wipe the MFT" and "Wide the disk surface" when doing a free space wipe on an NTFS disk.