As far as I know there is no real difference between a swing meter and a rate of turn indicator, although maybe there is, read further on. It seems that the internet has no information on the subject, in any case I could not find it. The biggest supplier of ROTI’s in the Netherlands is Alphatron and their product Basicturn is labeled ‘Rate Of Turn/Swing Meter’. I telephoned with the tech in charge but he said that he is unaware of a product that is more sensitive than a Rate Of Turn Indicator and that the term Swing Meter is just an American name for a ROTI.
I learned from him that their instrument still uses a real spinning gyro as that has the greatest sensitivity compared to the solid state gyro sensor. Maybe that explains it, a Swing Meter has a real gyro and is more sensitive than a ROTI with a gyro sensor. Well, that is just a little theory without proof yet!
Tomorrow I will call another, also a rather big supplier for that kind of equipment and see what they have to say. Keep you informed.