cbsewell :
What if the contents of those folders are different over every device i have? If I enable desktop/documents/pictures on each device, will they all be mashed together? What about shortcuts to device specific files? What happens if there are duplicates?
It will very very likely merge each respective folder. Anything/Everything under the folder "desktop" on all your machines will appear on all your machines.
If a file with the same name exists on more than one machine, a hash is usually compared. If the hash matches, then great they're the same file and nothing needs to be done. If they're different. The tool will do what any file syncing tool does (dropbox, drive, etc), it will keep both copies by either appending "from machine XYZ" to each file or "(1)" and "(2)" to each file to differentiate.