Going back to Mavericks: will i lose my files that I have created on Yosemite?

FileVault slowed my MBP. So, I am going back to Mavericks. How can I make sure that my files saved on Yosemite will not be lost? If I go back using Time Machine, how do I access my files that were saved on Yosemite? Do I have to make copies of all these files on a separate flash drive bf going back using TM?