Its been about 4.5 years since I bought my wife a 27" iMac i7. It came installed with Lion and I have been too scared to upgrade the operating system. For the past three years or so I have been using TimeCapsule via an external USB hard drive, but I wonder about what precautions I made need to focus on before seriously upgrading the OS X environment. First and foremost is the need to protect the wife's data. Then there is the potential impact of installed software (Lightroom, Office, ACDSee, etc.) being effected by the operating system being upgraded. Lastly, I wonder about how system performance might change [for the worse] if I do upgrade. I did add 16GB of RAM to the factory installed 4GB, but one might say the CPU could be getting long in the tooth. I have previously purchased/acquired, but not installed, Mountain Lion and Mavericks. Any thoughts on the coming approach of all things paranoid?