TLDR; yes, it is possible to add an SSD to a 2011 27" iMac without going through too much hoopla. Between everyone having issues finding parts, non-workable guides (due to parts), and general ...

So what if you've done everything you can, but your iMac is still sluggish? Grab a speedy external SSD and do an OS X brain transplant!

The teardown team at iFixit has taken the time to give a full run-down to the iMac reboot series appearing this week from Apple. What you'll find is a build quite similar to last year's collection ...