Been researching the coveted Rolls... Of the readily available models, which is the preferred model and why?? The early Viscount with the single Greek key pattern? Or the later Whetter with the three key pattern..?? I see there are some differences in case design, but this seems to be cosmetic only, but there are also differences in the handle design which could prove significant.. I don't know which handle belongs with which model.. I also understand there a differences in the materials used in the various models.. Nickel versus ??? for the blade and Steel versus Aluminum for the case.. Anything else to be aware of?