It was my understanding that a Deployer Extension was not an officially supported extension point in Tridion and Storage Extension was the supported type which accommodated the same need to perform custom logic upon deployment. However, I have just checked the 2013 SP1 docs and see that they provide instructions on implementing custom deployer modules: http://sdllivecontent.sdl.com/LiveContent/content/en-US/SDL%20Tridion%20full%20documentation-v1/GUID-DA883F20-294E-4D96-BBDA-1EBDB1C42DBB
So if both are now supported, how do I decide which to use, i.e. in what sample scenarios do I use one over the other?