It's safe to upgrade to 10.11.1 AFTER install EL CAPITAN. I'm already running EL CAPITAN in my MAC PRO 1.1. and works perfect. It's was installed (in another MAC with external USB case for de SSD HD that I use on my MAC PRO) using this method: Then, after installation, copy Pike's EFI32 boot.efi to that drive's /usr/standalone/i386 and /System/Library/CoreServices/ directories overwriting the stock Apple EFI64 boot.efi and repair permissions. Now I want to know that IT IS SAFE to do the APP STORE UPDATE to 10.11.1. . THANK YOU.