I have always thought that the softbac on salix gloves referred to the inside lining for the back of your hand which is nice and soft and comfy? Didn't think it referred to the palms? I don't know for a fact though?
I have only ever seen it on Salix gloves now that you mention it. When I am there ( at Salix) next week I will ask and let you know if it hasn't been answered by then mate.
It's the backing of the glove thats in contact with the rear of your hand, the majority of gloves (any that are half decent) will have it but most just choose not to highlight it as its not really a UsP