Well, of course I'm an amateur here - I have a PhD in mathematical physics, and am best known for having proved that chaos theory is undecidable and Gödel-incomplete in its axiomatic form, so my formal training is outside linguistics. My interest in linguistics in this particular case has to do with the birth of philosophy: how much of the Hittite cultural aspects has been carried into Greek thought?
Yet I wouldn't call Margalit Finkelberg an amateur..
But you have not given us anything at all concrete to work with from her book. The -tt- and -nth- stuff has been bandied around since at least Palmer in the 1930s and I'm sure much longer. What new and useful information does she provide?