Got a memory foam mattress 3 years ago, most comfy sleep I've ever had. I'm now unable to get a good nights sleep on anything else.
Our plumbing went in the loft and the majority of the water leaked out onto our bed (thankfully we were not in it as that would have not been a pleasant experience)
The foam retained about 99.9% of the water that fell on it effectively saving the living room and electricals from being damaged.
Been at my parents house for a while now, not slept nearly as well and am getting a bit of a sore back. However I got a memory foam pillow the other week and that improved my nights rest considerably, however the bad back has not diminished. Cant wait to go home and sleep on our new memory foam bed.
So Memory foam, great for sleep, great in a flood situation.