Tempur-pedic does offer a three month trial period, if you don't like it they take it back.
We have one and hated it for the first few nights, but after a week we decided it was heavenly! We've had it for about three years now and I'm starting to fall out of love with it, as the foam ages it becomes more susceptible to heat which means if you spew heat like I do it makes the mattress softer. By the middle of the night I'm sunk in and it makes my back sore...I called the store where I bought it and was told "sometimes that happens, you can add a mattress pad and that should help spread the heat out.

For a $2000 mattress I expect it to perform flawlessly for much longer than three years.