Equity Library Theatre did a full, but stripped down production of Allegro in about 77 or 78 which I saw. I had the hots for a cast member so my memory is prejudiced, but I remember saying it had problems but was still on the good side.
Also wasn't Allegro done the very season of Encores?
"The gentleman is a dope,
A man of many faults.
A simple Joe
Who wouldn't know
A rhumba from a waltz."
or something along those lines. It is the most "Hart" of Hammerstein's lyrics.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher