I found this tip while browsing today. Using it you can get up to 6 rows of tiles on the Surface 2 home screen. I suspect it will also work on the Pro although I have not tried it
Run more apps and show more tiles on your Surface 2 or high-dpi Windows 8.1 Laptop - Scott Hanselman
Enjoy
Run more apps and show more tiles on your Surface 2 or high-dpi Windows 8.1 Laptop - Scott Hanselman
Enjoy