Jupiter put on a great show tonight!
The impact feature is still hanging on and was readily visible through my 8 inch Dob at 120X and 240X. The best part was the addition of a beautiful shadow transit with Callisto hanging just outside Jupiter's following limb. It also provided a nice contrast for comparison of the two spots. Callisto's shadow was strikingly black, while the impact scar appeared more as a soft feature that seemed to take on the brownish color of the surrounding clouds. I spent more time getting a feel for the impact site itself, and did detect a horizontal elongation and slightly condensed appearance.
I finished the observation just as Callisto was dipping into Jupiter's profile. What a great view!