I don't think I'll be able to make it to the reading on October 24th, but the cast sounds great. It includes Stephen DeRosa, Jacob Ming-Trent, and Reg Rogers, who were all wonderful in Red Bull's production of The Alchemist last year, Michael Urie, who headlined the company's production of The Government Inspector, and Amelia Pedlow, who is always a delight to see on stage.
Personally, I find Cibber's play to be superior, but I'm in the minority. Many people found the last-minute reformation of its rake-hero Ned Loveless to be unconvincing, Vanbrugh among them. Within weeks of seeing the play in 1696, he penned a sequel in which Loveless relapsed to his old ways, carrying on with his wife's cousin, Berinthia, who comes to live with the couple after she is widowed.
The scene in Act IV where Loveless sneaks into Berinitha's chamber is shocking even today for its sexual frankness. Though Berinitha has already expressed her desire for Loveless, he resolves to "attack her just when she comes to her prayers." When she sees him, she cries out, thinking she's seen a ghost. When her maid comes, however, she convinces Loveless to hide again and sends the maid away so they can be alone.
Berinitha pretends to have virtue, but Vanbrugh makes it clear she is more than willing to have an affair with her host. The stage direction "very softly" accompanies her line "Help, help, I'm ravished, ruined, undone! O Lord, I shall never be able to bear it." Actually, she appears to bear it quite well, and not content with committing adultery with her cousin's husband, she plans to get her cousin to have an affair as well, scheming to get her together with Mr. Worthy.
Cibber's original play features two brothers with the last name Worthy, but it's unclear which (if either) of them is supposed to be the Worthy in the sequel. George Powell, who originated the role in Vanbrugh's play, was not in the original cast of Love's Last Shift, so audiences would not have immediately recognized him as one of the previous characters. In any case, Mr. Worthy in The Relapse starts out as anything but his name, openly trying to seduce the heroine, Amanda Loveless, in spite of being married himself.
Upholding a sexual double standard, the play has Amanda find out about her husband's infidelity but remain faithful to her own marriage vows nonetheless. In an extraordinary scene in the fifth act, Amanda converts Worthy from his sinful intentions and guides him back toward the path of virtue. The scene is written in verse, which is unusual for Restoration comedy. It ends with Worthy expressing chaste admiration for Amanda and rejecting "the gross desires of flesh and blood." Amanda gets virtue to triumph with her admirer, but alas not with her own husband.
If that sounds like a downer to you, know that the play's other plot revolves around the character of Sir Novelty Fashion, played by Cibber himself in Love's Last Shift, and promoted by Vanbrugh to Lord Foppington in The Relapse. (Apparently, Sir Novelty Fashion wasn't on-the-nose enough for Vanbrugh, who also named a character Sir Tunbelly Clumsey.) Cibber reprised his role in the sequel, in spite of not writing it himself.
Cibber might have been open to someone else writing a sequel to his play since Love's Last Shift was the first piece he ever wrote. However, Vanbrugh wasn't any more experienced, and The Relapse was his first play, too. (Would we all could have such success with our first plays!)