I paid more than $400 each for three rear mezzanine tickets to the OBC (minus Lin - who got sick that day - and Onaodowan) in April 2016 so I'm one of those crazy people. Feel free to mock.
That said, I wouldn't pay the same amount of money now to see any Hamilton cast, anywhere. Seeing the OBC was one thing. Options were limited, especially for people like me who needed multiple seats, and I don't regret it. You've got options if you're going to New York if you really want to see the show (cancellation line, play the Stubhub waitng game).
Saying the touring cast you'll see in Toronto in 2019 is better than the touring cast that I saw twice in San Francisco (now in LA) is a faulty comparison. The current touring cast is a different touring cast than the one you'll see in two years, just as the extended sit-down run that starts in San Francisco in 2019 will have a different cast than the one that just left.
These things are always a gamble. But given that, I wouldn't assume too much. Shoot, even if someone is on the Broadway cast or on tour, they might get sick. (That's what happened with Lin; I saw Javier Munoz, who, at least when I saw him, gave a terrific performance. Michael Luwoye was out the second time I saw the show in SF.) Things happen.
I can't speak to the overall quality of the current Broadway cast. Munoz is still Hamilton when he's not out. Andrew Chappelle, who I saw as Mulligan/Madison, is back as the supersub. One advantage of seeing it on Broadway is the smaller size of the theatre.
But people get desperate about this show. With so many touring productions, it's actually not that hard to get face-value tickets if you keep an eye on things. Don't panic. If you really want it to see it on Broadway, I am confident that you'll be able to see it for less than $400 a ticket.