If the JK had a U-Joint style double cardin shaft like the TJ's do, I could see what you are talking about. The increased angle would cause stress at the U-Joints and this is typically seen/felt in the form of vibrations. The JK's have CV joints much like an IFS vehicle has and are designed to be run in steeper angles without any issues. Now, on a 2-door, the shaft will be at a very steep angle and while this will not cause any vibrations per se like a TJ without an SYE installed, it will leave the CV boots in a constant pinch and will ultimately cause them to wear out prematurely. Once compromised, water and debris can get in and cause the joint to fail. But, stress would not be a factor on this drive shaft either. In a nutshell, the JK is a very different vehicle than the TJ. Trust me, I own both.