An alternative point of view is that the cellular mirror is 4 times less stiff than a 4" thick monolithic mirror.

Yet another point of view is that a 2" monolithic mirror has plenty of stiffness. One can argue that there's no need for the cellular to be twice as stiff, and that the cellular could perform perfectly well with only 3" thickness instead of 4". In other words it's not truly an optimized design

.

The bottomline: all this is more marketing than science, don't let the engineers bamboozle you!

Robert