To be honest I am not sure. We have the Liberator Wedge/Ramp combo, the wife does not like the firmness and says they are uncomfortable during sex. They are nice to use while watching TV or playing video games. I use the Wedge during solo time for anal play and have no problems there.
The Lil' Pony looks like it could be fun for solo or partner time, the pocket could come in handy if a vibe were placed in it during doggie style.
I am awaiting on the Curve to arrive and we are excited to test it out. We are hoping the smaller height will prove to be more comfortable during sex.