Personally, i think it depends on whether you have a suspended floor or solid floor as to which one will suit better, or give you more oomph. Suspended floors will absorb to an extent, whereas a concrete floor will 'reflect' (best word i could think of) whether it's bare or carpeted.
Many people say that it doesn't matter which way a sub is facing, or how close it is to a wall. Just place your sub firing into a corner and compare it to how it sounds in the middle of the room. Face it towards you, then face it away from you. Difference? It may sometimes be subtle, bit i think so.