if I had the time, I would put these seat stay gussets on every frame. The stiffness is really apparent switching from any other frame. This is a really long frame so it needs some extra strength. The slightly longer (5") headtube distributes forces better as well.
Working on Ti while the Supertherm top tube shortage continues. I have some smaller 1.25" top tubes coming for some other projects but the normal top tubes have been more than seventy days on back order and still haven't even reached the supplier. Another option is a 1.5" Supertherm top tube.