I'm getting the Pro next Friday and installing a 1 TB external. I'm actually removing the 1 TB I had put in my OG PS4 and re-installing the 500 GB one. I have an external drive case I will slip the 1 TB into and just use it for that purpose.

It's funny. I never thought 1 TB wouldn't be enough space. But with myself, two kids and their PSVR games, I can't put any and every game I want on the system. 2 TB gives a lot more breathing room, especially since 100 GB is just taken up by the system.