here's the measurement we've got from S3 on tractrix 260 horn.
the increments on the graph are 1db
it seems useful from around 450-500 to some 1.3k, but it still looks very bumpy in comparison with a number of other mid drivers aiming the same range.
not sure if the measurement was correct due to proximity of the mic from the mouth, but we certainly didn't have an anechoic chamber for more proper measurement.
EDIT: PS. i apologize for opening a new thread, i've actually wanted to post this bellow a S3 talk in the forum.... maybe it can be moved there ?