Whilst more and more organizations have made the jump from XenApp 6.5 to 7.x, it seems many more are still hanging around on 6.5 or even earlier versions. While I don’t agree with doing that, I can understand it. With all of the work and revs that went into 6.5, it was a very stable and reliable product. It seems to me that most middle to large sized companies used XenApp and I would hazard a guess that most used 6.5 at one point or another. Defacto, many IT professionals have experience with XenApp 6.5, they like it and they are comfortable with it.