We've just begun the process of storing 500millions+ files into a GridFS server farm, and we're not comfortable with the default md5 hashing method due to the birthday paradox, currently we have to calculate a stronger hash ourself and then save the file with it, after that we run another command to remove the default md5 hash to save some space.

It'd be much quicker and simpler if mongodb can let us choose different hashing algorithms when saving files, md5 is for the 90s