i have 2 ps4s. afaik xbox has the same concepts though but again,.. i'm speaking for my experience as a 2 ps4 owner.
when you buy something digitally you get 2 licenes:
1. hardware licence that is tied to your "home" console
2. software licence that is tied to your login.
that means you use the same purchases on two consoles. basically make one console your home console and anyone can use anything you download to that console via your account.
then on the other console you can still access your entire library so long as you are connected to the internet. if there is an internet outage as sometimes happens you'll be locked out of accessing your content.
so here where my "surprises" or lessons learned.
you cannot log into two consoles at the same time with the same account. that means i had to get my wife a psn account to login into the "home" console to access my content. also be careful about logins,... i had to set up the "home" console to automatically log into her account because she was accidently logging into my account on occasion. that got me kicked out of my account in the other room.
some services cannot be shared. spotify is tied 1:1 with a psn account. i had to sign her up for a spotfiy account too because i wasn't allowed to use my spotify login info on her psn without deactivating the account on my psn. this was okay to me because i don't pay for spotify.
some services can be shared but don't allow multi usage. amazon let me use the same amazon account on multiple psn accounts but they do not allow streaming to multiple devices at the same time. so either i buy a second amazon prime membership (no thankyou) or we just can't watch that service on both tvs at the same time.
some services can be shardw and allow multi usage. netflix is awesome. i love netflix. also hbo,.. hbo is great.
peripherals can be awkward. i purchased rockband 4 with the intent to use my BC supported guitar from the ps3. it works great when in the game as an input for gameplay however the system doesn't register it as the same thing as an actually ps4 peripheral. long story short,.. i can play rock band on my "home" console but not on my login-console because the system doesn't acknowledge me as logged into the system.
tl;dr version: 2 consoles works great for sharing your game library but can be awkward with some of the services.
