I've got an RC30 and I couldn't be happier with it's capability. I use it more for practising by layering tracks with the onboard drum samples and recording various guitar/bass parts. The onboard drum samples whilst not editable are good and I can generally get something suitable from the 8 programmed rhythms - the on board effects are good too. These, and the much longer recording time available are the main differences to the RC20. The quality of the recorded/layered sound is excellent and I doubt if I have scratched the surface of it's capability. However, even with the way I'm using the unit it's great fun andf the most used pedal I have and I can highly recommend it.