Harmonic syncopation, until when/how much is it debatable? I am asking because it was "noted" during a workshop and I wondered, if I wanted to use it ... because sooner or later I will be able to do so, when, where and how to do it?
The concept of harmonic syncopation is only valid in certain stylistic contexts.
Some cases in which it is bypassed can be chorale incipits (false anacrusis due to the syllabification of the text) and pieces for piano - voice and piano - instrument and piano (especially in the "extensions" or in the "maintenance" of certain harmonic passages: see Mozart, piano sonatas, and Schubert/Schumann, lieder). It is also often found in hemiola (from Renaissance-style compositions to the late nineteenth century, Brahms is a master of it) and in any case where a shift of the harmonic-rhythmic accent is required.
However, hemiola isn't exactly a harmonic syncopation... or am I wrong? I seem to remember an example of harmonic syncopation also in Beethoven... perhaps in the piano sonata, 'The Tempest'