Fascinating thread - big cats in the eastern US are one of those topics that official bodies keep batting away despite the volume of credible sightings. The Blue Ridge area has a long history of these encounters going back decades, well before the internet made it easy to cross-reference reports.
What strikes me is the consistency of descriptions across completely unconnected witnesses. Black colouration, large size, long tail with a distinctive curve at the tip. That tail detail keeps coming up and its not something someone would automatically invent.
From a cryptozoological standpoint the most plausible explanation is either escaped or released melanistic leopards, or a relict population of eastern cougars with occasional melanism. Neither is particularly comfortable for wildlife authorities to acknowledge.
If you can get back to the location, note the exact substrate you were on and look for prints or scat within 50 metres either side of where you spotted it. Photograph anything against a scale reference. That kind of physical evidence is what moves these reports from anecdote to something worth submitting to a proper database. What time of day was it and what were the light conditions?