I guess one reason also I ask about the rear suspension is that it would appear to provide a smoother ride for the back, but unless you are riding the surface of the moon maybe a solid rde with no rear suspension is just as smooth and easy on the back.
I guess since I have a back condition (LSS - Lower Spinal Stenois) I want to protect my back from harm as much as possible, but at the same time I don't want to discount a bike just because it does not have a rear suspension and I am afraid of getting a jolt to my back.
It does seem that the newer 'bents have suspensions more often than the earlier models.