To give you a comparison of what your "testing" achieved:

Ask a friend to watch yourself kill ennemies while you use a set with 15% crit rate and another with 22% crit rate, without telling him beforehand what you are testing. Afterwards, ask him to tell you if he thought there was a difference in the speed at which things died, and if so which one was the fastest. There is no way for someone to give an accurate answer to this. Not only watching with the eye is not accurate, but you WILL crit more with the 15% set than with the 22% set on a non-negligible number of fights. 15 to 22% crit rate also imply the stacking of over 150 crit rate in stats. This doesn't mean crit rate is negligible. It is just very hard to evaluate its impact without proper tools, as is parry.