I am considering upgrading my Mac to hopefully prevent any slow down over the next couple of OS X releases. So my plan is to get an SSD and upgrade my 12GB to the max of 16GB. I should mention I have a mid-2011 21.5" iMac. I've thought it through and decided I have 3 options as followed #1 - Paying a local authorised Apple service centre to install the SSD into my iMac #2 - Installing the SSD myself #3 - Using the SSD externally via Thunderbolt with the Seagate adapter. Question is, what option do I go for? What would work best/is the safest?