I just got mine and after about 5 minutes I'll recommend this be sent out with every unit going forward, or at the very least an optional upgrade.
Pulp Fiction comparisons aside, this absolutely solves the problem of the current velcro strip, which is the nondurability of the contact point of the bottom. I've been trying myself with homebrew solutions involving lots of tape and long strips of elastic, but a full silicone case with a rivet is leagues beyond whatever I came up with.
It did take a moment to figure out how to place the clip (in back, not in front), and I have smaller hands, and my ability to hit the thumb keys is hindered slightly. I don't really know how you'd engineer a solution to that, but at the moment these are my only criticisms.
I'll keep using this and let you know if I have further feedback.