My experience with pillows like this is that they actually caused me neck pain. The pillow is generally too firm for my liking. If I am lying on my side, it doesn’t fit correctly in that 90 degree area of my head/neck/shoulder. As a result it holds my head up too much or it is down too much. Another problem is the impact on the neck. If I lie on my back, it puts the strain on my neck by pushing up on it. If I lie on my side, same thing. The head is always heavier than the neck so the head always sinks further than the neck pushes down. Every time I have tried a pillow like this it feels great when I first lay down on it, but as I sleep and my muscles relax, the pillow pushing up on the spine in my neck ends up causing problems.
I’ve been very curious about a Purple Pillow. Recently got a Purple Mattress and it is very comfortable. They had a Purple Pillow in the mattress store that I tried and it was very comfortable but not sure how it would work after a full night as opposed to the couple minutes I tried.