I'm visiting Austria in August and will be taking a train from Vienna central station to Hallstatt. RS's book and most articles/posts reference needing to transfer in Attnang-Puchheim. But both "Rail Europe and OBB show a direct train with no transfer. Has anyone taken this train? I just want to make sure I'm not missing anything and that this is perhaps a new direct route.
ÖBB is the company that actually runs the trains. They know what they're talking about. If they show a direct train, there is a direct train.
I seem to remember that there is one direct train a day. Bòk it, if the booking works, you are on your way. Sort of.
There is no new route. The direct train just skips the change in Attnang-Puchheim and is about 15 to 30 minutes faster, depending on the time of day. The direct train departs at 8:40am every day from Wien Hauptbahnhof (main train station).
Avoid Rail Europe, book your tickets here: https://www.oebb.at/en/
If you check "Direct trips only" on the search page, you should get one result per day only.
If you uncheck "Direct trips only" on the search page, you will get a lot of different options, but resort to those having one change only (in Attnang-Puchheim). This change is no hassle, I had done this trip last year. The change is on the very same platform, so the short lay-over is no problem. In the very rare case that the train from Vienna is delayed and you miss the connecting train, there is another train about every half an hour to Hallstatt.
Make sure to buy seat reservations along with your train tickets, especially for the direct train.