I don't have a 5-link rear axle. But I have to say that with my two Morgan where the shock absorbers were adjustable it was always a better ride when it was softer in the back than in the front. This is probably the same with 5-link as with conventional suspension. I also believe that it is basically due to the structure of the flexible ladder frame. And one shouldn't force this ladder frame into something that isn't its nature by choosing a too hard rear setting regardless of the axle type.
