I think I saw A Chorus Line 10 times over the years including the original cast and the dress rehearsal of the record breaking performance. The original cast was 'special' in every way because they were our peers. We 'knew' them (or of them), some of them personally. The show worked on that level then.
However I saw the show with casts that were complete strangers to me and it became more powerful because there was not the extra baggage of knowledge.
The less we know about the actors, the better we know the characters.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher