You will not need an acrlyic tank, for any species of mantis.
100% of the time, when you hear of them breaking glass, it's the bottom pane of glass, due to their burrowing. This is mainly the keepers fault, for not providing a deep enough sand bed. The mantis burrows, reaches the bottom of the tank, thinks it's rock and pounds away at it until it causes a crack...they will NOT "smash thru glass".
You can VERY easily solve this problem by laying down a piece of plexi, cut to fit, into the bottom of the glass tank and then cover that will an ample sand bed.
I've kept a total of 4 Peacocks (as well as 5 other species) and have never once had any of them break glass. All were also kept in 20gal. tanks, without plexi and all grew to adult size (aprox. 5" - 6").
And, as others have said...a lid is a good idea. I had one get spooked, one time and jet out of the tank, only to crash a good 3', onto the hardwood floor, and break it's shell.