It's funny how things like this happen.  In 1995, responding from a commission from the Rascher Saxophone Quartet, Philip Glass made this third attempt at writing a concerto, with a double commission to write a piece fro Sax Quartet and Orchestra, and also a piece which would double as simply a Saxophone Quartet.
I can't imagine Philip Glass thought he'd be writing what has turned out to be one of his most popular concert pieces when he composed it.  In any case, the piece has gone on to become one of, if not the most, performed concert pieces in the Philip Glass catalog.  Rascher has performed it over 100 times and continues to perform the piece in both versions, and other Quartets have taken up the short work.  Here is a performance from last week with the Erie Quartet performing in Fredonia.  Other most frequently performed concert pieces must include the Violin Concerto, the string quartets which have been embraced by many ensembles, and the third symphony.