Just to add … my 09 didn’t have the newer thicker rear tiangle, still no problem.
I did switch between sizes though.
I’m about 5’9″ so started with a medium … I later switched to a Yeti small which is a 17.5″ frame and not a stretched as the medium … so depending on how you like your bikes just be aware that a Yeti medium is around 19″.
great bike though whichever you choose … the only reason I changed it was due to not really needing nearly 6″ of travel for the riding I regularly do.
pic of the bike is the ‘small’ frame