I have a 2TB HDD (ordinary notebook HDD) inside my PS4 since Day 1.
Really, it's easy as hell to swap the HDD inside the PS4.
Max. 5 minutes, the last time I did it.
Is 2TB the most you up upgrade to? I'm not really a fan of deleting installs/patches, on PS3 you can just delete installs and keep the patches, so deleting installs isn't a big deal, whereas I think the PS4 adds the patches to the installs, so uninstalling a game means also deleting the patches
I don't have the best internet speeds in the world so I'd rather just start with a monster hard drive and only uninstall stuff if I have no other choice