I am a power user. Two important ideas:
1) SECOND FUNCTIONALITY: Enable the use of SHIFT, CMD etc. modifier keys alongside your custom shortcut keys to expand functionality with a second shortcut. This approach effectively doubles the available options without requiring additional physical buttons.

As an example, let’s say I assign a custom shortcut to the 'Screen Capture' key. (eg. I use it to export Layer Comps in Photoshop). It would be even better if I could assign a secondary functionality to by using the 'Screen Capture' key in combination with the SHIFT key, for instance. For example, I would use it for another special export command in Photoshop.

This would also has a positive side-effect: Allowing a secondary shortcut with modifiers like SHIFT would also preserve some important default system functionalities—such as adjusting the volume—while still enabling custom shortcuts using the volume buttons.

2) NOTES: Let me add notes whenever I create a keyboard shortcut. (just a small empty field under the shortcut). Since we all use many apps, many users will eventually forget what a custom shortcut key is meant to do. Having the ability to include notes would make it much easier to remember their purpose.

3) Allow the user to export the settings to a local file, and import these settings back in case the user needs to reinstall the system or he/she buys a new Mac.

Please feel free to email me for clarifications or more ideas. Thanks!