I run a late 2013 27” i5 standard iMac with a 7200 rpm. HDD and am considering the option of an SSD as an external boot drive. Everything I read on MacRumors suggests there would be a dramatic performance improvement if installed internally, but, I do not want to go down this route. So, my questions are: a)Would external cabling cancel-out any improvement I would see if installed internally? b) If there was any improvement to be gained by installing externally, would this be worth the investment, or, be marginal c) Would I be better using Thunderbolt or USB on my machine. Thank you in advance for any advice received.