ZIMO decoders have excellent motor control, but yes, sound is less than optimal. They have rather sparse selection of American prototype sounds, and what they offer is usually not all that good (some sound projects are quite old). They function assignments and features are also unconventional. They are Austrian company and they are really concentrating on the European market. THey have good selection of European sounds. Also some sound projects have to be purchased from independent sound developers. ESU has them beat as fsr as American (free) sound projects.