This is one of the best graphic representations of the speed up/slow down issue with driveline u-joints - https://www.youtube.com/watch?v=DDmz0tibVGM

I can see that it applies to steering u-joints too, but I believe that the impact of it is not really much of an issue in the steering geometry since the speed up/slow down would only be seen in a rapid multi-turn maneuver. It's a real problem with your driveline.