Since the new Mac OS X 10.11 El Capitan is brand new, I recommend installing it on a separate partition on your hard drive. This will keep your current Yosemite system safe from harm, and will let you easily switch back to it should El Capitan become unusable for any reason. Dual-booting will also let you uninstall El Capitan easily (you just delete the partition) should you decide you're not ready for it. You will be stuck with the El Capitan recovery partition, though, so you won't be able ...
