Finally, it's here and usable!
The sln files have always been a hassle to deal with. My team has been using slnx for one project.
My main gripe was that VS didn't add it to the recent projects jump list in the task bar - so it had to be loaded via two steps - the file, or starting VS and then loading it from recent projects. Can't wait for that to be implemented because I usually open my projects through the task bar jump list.