Air Forums Sprinter and B Van Forum
Your questions have been asked by others on that forum - some people have no problem with the smaller Class B, and others cannot tolerate the restricted space. It all depends on the owner's temperament and intended travel lifestyle and, to a certain extent, willingness to develop small-space workarounds.
My husband and I don't mind the smallness, but our secret to that was extensive modifications. Our Interstate feels larger every time we add a new functional capacity to it. We've spent much of our free time over the past 2.5 years doing just that, so we've got quite a versatile rig by this time.