I'll underscore your awe by reminding you those solar masses disappeared in only 1 tenth of a second - the length of the gravitational wave signal.

but that's the time that passed here... it sounds like a mind-warpingly different perspective might have been seen there

I think you have it backwards. From the POV of someone near the Event Horizon, other space speeds up. Galaxies begin to spin at noticeable speeds.... But the black holes would appear to be approaching each other at "normal" speeds.

Dang