Here is a link that will enable you to toggle back and forth between the previous mirror's 9 point and 27 point deformations every time you place your mouse over the link.
In this case, more supporting points dramatically reduce the mirror's deformation due to sagging.  This is a relatively thick mirror of 2 inches, at the 20% upper limit for thin mirrors that can be analysed by Plate Theory.
For a comparison, let's take a look at a 10" mirror with a 1.3 inch Secondary and a 54" focal length that is only 1.25 inches thick:
Now this link toggles between the 9 point and 27 point deformities of the one and a quarter inch thick mirror.
The benefits of a "Plop" optimized mirror cell for thin mirrors is obvious. The 1.25" thick mirror is almost as good as the 2" thick mirror in their respective 27 point cells.