Looks like a great job on the Miyata copy. It looks really tough and would directly replace the Miyata in a way that is gym floor friendly. The Bruce Edwards fix is beautiful and cheap but labor-intensive and allows metal to touch the floor.
To me, though, the design of the Miyata and KH handles was dictated by plastic molding technology or something similar, and freestyle use. For more forceful handle use, such as trials, off-road, or even road touring/racing, a more ergonomic grip is necessary. More specifically, a grip that provides long-term comfort, support and room for each finger, either excellent grip friction or provision for a covering that provides that, and compensation for wrist and arm angles.
Chris Reeder was on the right track when in his prototyping specs he stated he wanted a convex handle, not a concave one. There are three handles on the market now that provide that: the Reeder handle, the GB commuter handle, and the Kinport handle drilled and modified with cloth filler tape . It is possible to provide some convexity to the front of the Wilder handle with filler tape, but not nearly to the width required by the human hand.
The Miyata paradigm is not suitable for forceful applications and needs to be abandoned. The only things it really has going for it are a) it provides a nice springy bumper for protecting the unicycle during freestyle practice, where UPDs are many per hour, and b) it is light, c) it provides enough grip for occasional hopping and mounting use during freestyle or light road use, and d) it is ambidextrous.
Scott, please consider these remarks and think about this: for the more vigorous handle applications, design a new handle. Use the specifications mentioned above and put your great, powerful materials technology to use in an ergonomic handle. Make clay and wood models of hands and research grip friction technology. Look at the handles that work well for forceful applications and ask why. If you do this, and apply the same know-how that you have obviously done so far, you will have the best, lightest, strongest, most comfortable handle available for forceful handle use.
The other advantage to splitting your handle into two designs should be apparent: the Miyata handle, which you have made already, is perfect for freestyle and light use, and acts as a direct replacement for all the manufacturers-defect Miyata handles out there. There is no more design work to be done (except apparently for some mold work which I know nothing about)! There’s no need to open up this or round-out that.
My two cents.