Has anyone booked their Bernina Express tickets using the DB Bahn (booking Singen to Tirano) rather than booking via Rhätische Bahn? The Man in Seat 61 recommends this. We are staying in Zurich and wouldn't use the first leg of the trip if we did this. I know that we need to book a day earilier than planned to handle this first leg of the trip but it is so much cheaper than booking Chur to Tirano using Rhatische Bahn. Has anyone experienced problems doing this and waiting to board until Chur rather than Singen?
Here is a recent discussion on that same topic.
https://community.ricksteves.com/travel-forum/switzerland/tickets-for-bernina-express#top
We did almost-exactly that in 2016 (our ticket was from Freiburg Germany to Tirano, not Singen, but same principles should apply).
With the DB ticket, you just get the Bernina Express reservation supplement through their website (select "ticket available" on the pricing page).
As long as you have a ticket from somewhere "behind" Chur, to Tirano, and a Bernina reservation, you will have no problems.