Kinda late to this thread, but....
The new diamond infinite edge “pro” has an improved back wall. It is certainly not rock solid like my bow, but with the amount of adjustment it’s a pretty good compromise.
My 9yo has been shooting a Mission Menace for a few years. My 7yo has the newer Infinite edge.
As much as it pains this Mathews shooter to say, I think the Diamond is quite a bit nicer.
I would not hesitate to buy another for a youngster. I probably would not get one for a teenager/adult as I feel you loose somethings with all the flexibility the Diamond offers.