a715a371_on__Hardside_Softside_Mattress__0
[1] c+ [2] b [3] Owner experience data suggests that soft side waterbeds provide more comfort and support resulting in somewhat better pain relief, including back pain relief. About 18% of owners report pain relief, while 9% complain that their bed causes pain. (See mattresses and pain relief for more analysis.) Also, the "hard side" of hardside waterbeds can be uncomfortable when getting on or off the bed. [0] 
Less (back) pain
Unbiased Waterbed Reviews and Ratings 2014 : Complaints, Advantages, Disadvantages and Comparison: Hardside Softside Mattress
0