a few things i've found online regarding upgrading the drive/transferring files
"I still haven't found any information online about whether you can change the hard drive.
They are adding the ability to transfer information via ethernet cable from any PS4 to another PS4 if they both have the 4.0 firmware."
"If you look at a picture of the back panel, the lower right side
looks like a piece of plastic that can be removed that's about the size of the HDD. Where all the Dolby and other legal fine print is."
"Hey guys, I was wondering the same thing so
I tweeted PlayStation and they got back to me confirming that you could. I have asked them sizes etc. but nothing yet. I will keep you posted."
"Hi peps said I keep you posted....I have been on the case to twitter.....
The internal harddrive is replaceable. The physical size of the internal hard drive has not changed so it means anything that fits in your existing ps4 will fit in the pro and slim and visversa, meaning people who have a 2tb in there standard ps4 can put it in the pro and the pro's 1tb in your standard ps4. Even though pro is more powerful and probably easily able to handle more harddrive data, unfortunately Sony tells me that it still has a maximum of 2tb internal storage.
After getting all this info,
I then asked if the 3rd usb was for external hard drive or more vr in mind, all they said was " the 3rd usb could potentially be used for more memory". I think this means at the moment no, but once release is out there and they have ironed out s one bugs, it's something they want to add. When talking about pro to them, they couldn't stress more about the unison of the standard, slim and the pro ps4s. Which if they do make externa hddl compatibility on one of the ps4's good chance the other 2 won't be far behind.
Just keep in mind consoles work differently to a pc, SSD helps pc a lot, but not that much in a console, yes your game load time are about 15 seconds faster but that's about it. I put a sata 3 seggate 7200rpm 1tb in to my standard ps4 and it was glitchy so bad that it would crash and wipe my data, this happened to me 3 times, so spent some and put the sata 2 samsung spin point T9 5400rpm and works like a dream better than the original 500gb hdd. I know people that have had the same problem, and when they slowed the hdd down the system worked a lot better.
My point is that faster hard drives are great in computers but when put in the consoles it tends to over limit them, Sony chose these slower hdd for there consoles for a reason and probably had access to faster hard drives during development , remember they had 4 or 5 years to work all this stuff out. Sometimes it helps to listen to them.
Hope this helps"
Can you change the hard drive in the PS4 Pro? - PlayStation 4 - Giant Bomb