We've had our memory foam for about 4 years now, and desperately need a new matress! We bought it just before I went on a 6 month deployment, came back and it had sculpted itself to my missus lying in the middle, so no matter what we do (spin it round and stuff) we always tilt in!

Its absolutely true! It does retain heat far more than sprung matresses, I've just realised it now actually and never really though about it.

IMO their lifespan is less than a sprung matress, its no longer very supportive, and no longer gives us the good nights sleep that we once had.
