I'm curious about these, but would have to be able to mess with one for a bit before trying one.
I use two high density foam pillows stacked, slight softer medium thickness one on top of a harder thin pillow. Always try to sleep on my side, it's more comfortable for me and I tend to snore when on my back. I have had zero tolerance for down pillows since I was a kid, just plain hate them. I also really like to sleep on the leather sofa up at our condo and use the low, wide armrest to rest my head on instead of a pillow.