Already more than familiar with the intricate and twisted music you mention, I've re-listened all the quartets. It's mostly that I find the G.F. hard to digest in itself, and that I adore the individual movements of opp. 130 & 132 but fail to get the big picture. G.F. was supposed to be the finale to 130, but it feels an era of musical development is missing between them. My cd lists it as the finale of 130, with the later finale following it. Kind of absurd.