I've used them under the insoles to take up extra space. They might add a little extra cushion but likely negligible. I have the perfekt hikers but the heel cup is a bit big for me.
I love the large heel cups on the Meindl Perfekt Hunters!!!! Other boots give me heel blisters......never with Perfekt Hikers or Hunters. I prefer to use a heavy sock or two pair of light socks versus using the mesh insole as the insole seems to promote top of middle toe blisters for me.