I did my first install of 10.13 last night on a 2012 13' MBP without issue as expected but really have not looks at it yet. I posted this to see if anyone has done it yet, also because I know we will have question on it, and to see if anyone has attempted it yet and has any advice. I'm first going to try the install on a 2008 MacPro, then try it on either a 2008 and/or early 2009 MacBook Pro. But, after watching a couple of videos, right now it appears I will not have to do a firmware update. At the time I did it last year, it appeared that it couldn't be done on the 2008 MacPro. I did the Sierra upgrade on a couple of MacPros 4,1 and it has worked excellently, after I did a firmware update patch to get it to read as a MacPro 5,1, so I am very optimistic on doing it again. I am currently researching installing OS X 10.13 High Sierra on unsupported Macs.