So far works good for my laptops. But with android I already discovered 2 issues:
#1 Once btsync for android forgot the settings and I have to reconfigure sync again. Not a bit deal, but it was bad surprise to find out that files were not backed up as I expected.
#2 I discovered that file I changed on my ubuntu laptop is not updated on my smartphone during 2 days (the next folder is ok). Android btsync says it sees my second device, ubuntu does not. After I restarted my smartphone, data was synchronized. But wrong way: data on laptop was roll-backed to few days old status smartphone file has. Luckily, it saves "old" version in .SyncArchive folder, so I was able to restore my data.
So, I do not 100% rely btsync, but there is no other app that do the same.
You can install btsync and check if it works for you