Would it be useful in my dob with my Catseye tools? Particularly for bringing out autocollimator reflections?
No. In my experience the green filter is only useful for refractors.
It would make the autocollimator reflections darker.
If you have the Catseye tools, what you need is a lot of light in the tube.
With the AC, I point my scope to the west, up maybe 40° from the setting sun (so no direct sunlight enters the tube), to make all 4 images in the AC nice and bright.
And I use a white reflective center marker to make image 3 bright enough to see easily (images are P-1-2-3 in order of brightness). If your center marker is dark,
you will be frustrated using the AC.