I know only two Futaba gyros. An expensive version and one for "normal" use (good enough for learning it). The cheaper gyro has to be adjusted on ground (a good beginner value is about 8, then you can reduce it to 4 to 6), with the expert model you can change the gyro strength on flight. This is nessecary in speed fligth when the compass would over - compensate and the tail swings left and right.
To answer the 4 gyros: I gess there are only differences in the kind of bearings they have, but there is no need to get the "golden" models.
