Buoyen: I can't speak to the numbers for stiffness. But when I look at the length of engagement of the 3 axis to each of their rails, it looks short.

It is hard to judge from a sketch, over the internet, but I would like to see the engagement doubled.

again I don't know about stiffness numbers but over time the rails will wear, and the minimal engagement will show up more.

( every time I look at my Sieg X2 I am bothered by how little the saddle engages the X and Y axis.)