When I try to combine the book with boots, it just shows the X instead of the new item, with level cost. I believe it is this way partially because it spawned with blue text, and not yellow text, which worked in creative.
Environment
Java 1.8.0 (sorry for the lack of info)
Found this out in my SMP world as well. A Soul Speed book cannot be combined with another book or pair of boots with an anvil if you are in survival mode.