The U5030 has the Tier 3 Mitsubishi motor with 203 cu.in., while the new XU5055 has Tier 4 Shibaura motor with 135 cu.in. Does cu. in. matter for engine longevity in this case and would you be concerned with it? A dealer told me the new Shibaura Tier 4 motor is quiet, fuel efficient, and even...