I have one of the 2008 models and 4 of the 2009. The 2011 model is just a new paintjob and plays identical to the 2009. The 2009 model added the GT tech and as a result it plays a little more crisp. I also think they redistributed the weight a little as it has a slightly higher SW. In play the 2009 seems to have a bit more power. But the big difference is really the feel as the 2008 and 2009 each have their particular feel. It really comes down to what feel you prefer, the GT feel or the non GT feel.
3X PK Ki5 315
Tour Bite Soft 17