Can a normal fridge be quieter than one with inverter compressor?
I have not worked on Panasonic inverter refrigerators in the US but I do repair GE and Whirlpool and Electrolux inverter controlled refrigerators, and they are quieter than the standard style of compressor due to the gradual increase in speed. However, that does add one more control board that may have an issue in the future if you are concerned with durability.  I wish I had more experience with those brands... hope that helps some!