I didn't say there was no difference. I am merely pointing out that the difference is small compared to the difference between the two and Berserkers. I don't see the point in wasting gold or tokens on Knights. Either get Soldiers for free (karma) or use gold/tokens for Berserkers.
Using Soldier's Armor (weapons and trinkets berserker) is about 5% less dps than Knights armor. You might not notice that, but I certainly would.