HTupolev

I'm not aware of any thorough analysis of that being openly available, and it's not obvious that even the big manufacturers have characterized it very precisely. It's definitely clear that reviewers are bad at guessing relative stiffness differences in ride tests.
The marketing flies by the "laterally stiff and vertically compliant" line, but biomechanics are complicated it's not actually clear that maximizing torsional stiffness is optimal for pedaling.

I like how my Emonda ALR pedals, and the ovalized downtube-to-BB junction on that bike really isn't anywhere close to the optimal shape for resisting twisting. I also like how my '79 Fuji America pedals, especially during maximal efforts, and that thing's steel frame is quite whippy.
I wasn't entirely fond of how my friend's Pinarello Paris pedals, and that bike has a tall downtube-to-BB junction which should be very stiff against torsion. I quite dislike how my Campeur pedals, and that bike has considerable torsional stiffness between front and rear triangle because it's designed to stay firm even when you're rocking a heavy rear load around.