I have 3 computers all running different software(Snow Leopard, Mountain Lion & Yosemite), so I can only run Photo on the newest computer and my iPhone/iPad. I am perfectly happy with my entire library being on my iMac and a pared down version of it on the Mini and iOS devices. I do not have photostream enabled on my iOS devices, because I don't want all my pictures taking up room in the Cloud. I have lots of pictures that are simply houses/rooms that I would like to use for building a house some day and there is absolutely no need to have them on all my devices. Likewise, I have a bunch of genealogy photos that don't want to be uploaded either. Am I not going to be able to use the new Photo app on my new rMBP because I don't see the need for the entire library to be in the cloud? Can I keep the pictures locally on the new rMBP using Photo? Can I simply airdrop the pictures I want use the app or am I going to have to find a new app for my pictures?