I have been using it since 1.3 (I believe) and I used to be a big fan of it.
I think BTSync's strength was that it was fairly simple, somewhat more simple type of system where you could just share key and start syncing; no account creation required. Now it seems to be departed into more with a strong push to identify based access control and such. When they started moving toward that (I've tried their 2.0 beta briefly) I just felt Syncthing is where my usecase belong. (Simply, all I wanted was a solution to move and update files from A to B to C.)
It sounds like 2.0 still provides the same functionalities, but in any case, that 10 folder limitation will not work with me anyways. I don't mind paying for what I use, but I just don't think it's a implementation I prefer any more...