Thanks for you kind words @disarticulate @holtwick and @jhnsnc 
I do use the prosemirror state. But for me, the question was if it makes sense to use ProseMirror transforms to represent document changes. Currently, I simply replace the document state. This is easier to do for me. I didn’t see any immediate benefit in Transforms, because they are mainly used to calculate change maps and to provide undo-redo functionality. y-prosemirror has an equivalent to change maps and undo functionality, that work better in p2p scenarios. But @saranrapjs brought up a good point for ProseMirro transforms.
Today I started to adapt the code to use ProseMirror transforms instead. So don’t worry, you will get your transforms 
I also think it makes sense to support existing plugins.