I have an older iMac that I would like to now put OS X on an external SSD and boot from it, along with all the apps on the computer, but (edit: ) accessing everything else on the internal HD of the Mac by changing the system's home folder to that of the one on the internal, thus, in my mind, getting the 'best of both worlds'. Strangely, I must be the first person online to ask this question. Is this feasible to do? Would I experience all the benefits of the SSD with only having the apps and OS on it while keeping all other files on the internal? Should I buy a thunderbolt or USB 3 enclosure? Apparently this is another subject that just nobody knows about, because I see many people saying you can't external boot from USB 3, however, as I understand it, you can. But which is better for this? Scary so many people think you can't. Is this a feasible plan? Is there a particular SSD that is best suited for this? Also, what exactly is TRIM and why would I care? Thanks a lot for any help.