At the strut rods that's completely true. The stiffer poly bushing resists up and down movement, which adds resistance to the LCA moving up and down. It also resists fore/aft movement better than rubber strut rod bushings, but the added resistance to the LCA travel outweighs the benefit in the other direction. Which is why I have always recommended adjustable strut rods. They move freely up and down and do not allow fore/aft movement.
At the LCA it's the opposite. A properly lubricated poly bushing at the LCA will have less resistance than a rubber bushing. You literally have to twist the rubber to move the LCA up and down with the stock design.
Now, if you don't lubricate the poly LCA bushing it's different story. You have to understand the differences in the material and how the bushing functions. Unlike what most people think you can't just slap the poly bushings in there, never maintain them, and expect them to work properly. Maintain them properly though and they'll perform better and last longer. But you can't treat them like rubber bushings, because they aren't.