Sorry for the long delay George - I finally got around to playing with this and it's exactly what I wanted - thank you so much - it's very handy.
Fwiw, my use case is a pattern like `\t[^:]{0,20}:\s*([^\s].*)$` which I use to match `git status` lines like `modified: Some/File/With Spaces/In the Name.png`, and now I can put `"\(matches[1])"` in the field to make a `Copy Target File Quoted` action, which is super useful to populate shell lines. The real value add is the space handling - the repo I work most in currently has art files whose names often have spaces, and I often want to stage specific versions or reset them from the CLI, and this is much easier than fiddling with copying around the spaces (I am a clumsy mouse user at best).
Aside: I'm not sure if there's a standard community forum for sharing configuration tidbits like this - do you know of any? My google search didn't turn up a clear winner for "small standalone bits" (as opposed to "just copy my whole iterm and shell config").
- Robbie