Hi, I know it's not great practice to submit binary files to git, so apologies for that, but I asked on IRC how to get a binary change reviewed (there's no dev documentation on how to submit such changes) and this was suggested. You can also download the updated matcap here:

This update greatly improves the visibility of objects using the metal_shiny matcap, especially ones with flat surfaces, while keeping the metallic finish and touch of sharp highlights. It also enables the Specular Lighting control. Comparisons and explanation of changes: https://devtalk.blender.org/t/call-for-content-matcaps-source-file/9258/10?u=jonlampel

There were actually a few solid updates posted to that call for content thread from the original creators, but they were never implemented. Is there anything we can do to get those included?