I have made a few tests on Talk:Sandbox with a mock discussion. Nothing too complicate: there is a proposal, three users answering to the proposal and one user endorsing opinion of another user.
The problem is that new threading model make any non-linear discussion unreadable. Once there is a deviation from linearity, that's the deviation that becomes linear, while the main thread moves on the next level. In the cases I have shown the discussion becomes difficult to read (and even more difficult to summarise). In fact this threading model is simply counter-intuitive and does the opposite to what you would suppose. That's sad as this could have been a real discussion and this could have meant that Gdańsk would become Danzig (nothing personal, just a famous edit war, sorry).