I am 5ft 11 and ride a medium.
Friend I ride with bought a large and is same height, having sought Dave Turners opinion on sizing.
The head tube and seat tube on the large were a lot longer than the medium and meant that you couldn’t get the bars as low or the seat as low when using it for more playful DH type riding.
I am on the limit of my seat post extension, but it fits fine. I prefer a smaller bike (in a bmx stylie) to chuck around.
The 2009 model (which is what I have) has a steeper HA than the 2011 which got tweaked. I run an angle set in mine to slacken the HA off by 1.5degrees and its made the world of difference, also a good bike to fit a CCDB shock to – really transformed it.
I suspect your be better on a large as the biggest option, rather than XL, assuming you are very close to 6ft.
Hope this helps.