The Saatva Classic 11.5" is compatible with the Saatva Adjustable Base and most other adjustable bases. The thicker 14.5" Saatva Classic mattress does not have the flexibility required to work with adjustable bases.
There's absolutely no difference in feel and durability between the two Saatva classic height options. The two options are mainly aesthetic and based on your bed height preference or if you plan to use your mattress with an adjustable base.
Learn more about the best mattresses for adjustable bases.