Seat reservations are now open for the new Goldenpass Express train that will run between Montreux and Interlaken without the need to change trains along the way. The first journey will be on Dec. 11th.
You can read all about it here
And book seats here
After posting I realized that this reads a bit like spam. Just meant as an FYI if anyone is interested. I have yet to actually reserve a seat on a Swiss train, so not sure if I will try this out or not. Could be good though.