On a scalloped fingerboard the fingers never touch the fingerboard but only the string, behind the fret. On a normal fingerboard the string is pressed on the fingerboard by the finger and the finger touches the fingerboard, transmitting the heat of the human body to the colder environment of the fingerboard. The denser the fingerboard wood the faster is the transmittance of the heat from the finger to the fingerboard, hence an ebony fingerboard which is denser (and also colder) than a rosewood fingerboard will have a more immediate effect of the phenomenon. This transmittance of heat from the finger to the fingerboard added to the effect of touhing, which by itself cancels out topical vibrations on the surface of the fingerboard at the touching point of the finger, serves to give an extra warmth to the timbre of the sound, cancelling however many harmonics that would have given the sound an extra brilliance and a very full attack on the sound. So, on a normal fingerboard by the above function we gain warmth to the timbre of the sound and we lose on brilliance and attack. Contrary then to this function, on a scalloped fingerboard, since our fingers never touch the fingerboard, we gain brilliance on the sound and a very good attack on the sound, however we lose on the warmth of the timbre of the sound. In both cases and in each one seperately, one wins something and loses on something else. Once you know these details you can arrange as a luthier and as a guitarist all your other factors accordingly to get the desirable balance for your specific needs. Nice topic, keep well, Yorgos.