re: STS 64, the most beautiful flight!
I'm pretty sure SAFER was never tested around the HST. But there were tests during one or more of the ISS related flights (Jerry Ross once did it).
But the most interesting untethered flight ever (even counting the MMU ones in 1984 ), was during STS 64!!.jpg)
The backpack is discreet compared to the MMU, the spacewalkers were close to the cameras, yet free, and they exercized with all kinds of pirouettes, tumbling motions, all with the background of Earth and space. I have the video of the flight and couldn't resist adding some classical music to it.
When it will be time to put the video into a dvd, that mission should get a special treatment.