Hi Friends,
I wonder that none have related to the clavichord..(It is said that Bach constantly had a problem with his clavichord due to the wonderful possibilities of expression, that caused him to weep into the instrument..(Quoted by several auth..tho' I can recall none....)..)
Perhaps overstated; however I have played clavichord for a very small audience when I was studying early keyboard techniques in university..(I assume all know why the audience was small)l...It can indeed be expressive..where to accomplish such an effect with the harpsichord depends on ornamentation...AND the actual literature...
I never cared much for harpsichord; it seems limited to me, a person given to extreme romanticism, but I recall the instruction I was required to take, and still believe it's content.
While ornamentation certainly expressed the style of the day, and was first and last a PART of the keyboard of that day, the simple truth is that the sustain time on the harpsichord is somewhat short, and at least in part, long trills aided in a connected and sustained line where need, (Which was not often, given the literature of the harpsichord...),and was surely a part of the purpose of long trills. Also recall the rather large change in touch required when additional registers were added..(actually rather uncommon on most instruments for much of the era...)
Of more interest may be the possibility of extreme expression on the clavichord, as mentioned above. It is a fact that fine instruments are available today and are worth some time in study...I did in fact sell mine, for cash for another instrument, soon out of college

I can say that none relates to the piano anyway; a completely different technique comes into play for piano...
John Cont