There are doctors who find it relatively easy to remove medpor implants, or so they say. First I'm hearing of medpor implants causing more infections, I actually thought it to be less likely to get infected than silicone. It's not treated so much as a foreign body the way silicone is.
There IS a notably higher risk of damage to the chin when removing a medpor implant as opposed to silicone. Many doctors do not want to remove medpor implants for that reason, so you'll have a hard time reversing the surgery for whatever reason. Medpor implants WILL eat away at the bone beneath it, just like silicone does. Also, some patients don't like how medpor feels in their face vs silicone. Best approach is a custom silicone chin implant or custom wrap around, imo.