Got 512 Gb because Pro Res videos are 6 Gb/min heavy and with just 256 Gb storage you can take max 20-30 minutes movies (together with OS, photo library and apps already installed) which is not enough most of the times you want to take movies.
BTW don't expect the transfers to Mac/PC/iCloud will be that fast with the lightning cable, you may take half a day each time and you may lose the event you want to film while transferring the previous content.
BTW don't expect the transfers to Mac/PC/iCloud will be that fast with the lightning cable, you may take half a day each time and you may lose the event you want to film while transferring the previous content.