so I went ahead and got the XsMax 512 GB because i had already filled up my previous X. I have a 2015 iMac retina 5k with the 1TB DRIVE. when I go to back up I get the message there isnt enough room and cant back up. I have now gone to the extreme of removing a ton and have 550GB on that drive. STILL getting the message! I even deleted all prior backups in iTunes. Is anyone else experiencing this? How much space do i need on the computer to back up this phone? I only have about 240GB of files on the phone. This is driving me crazy. Has Apple created a problem for those of us backing up to computers and not iCloud?