I agree with canton7 here.
My “personal” part of syncthing use is quite enormous: >3TB of data in >300K of files.
I have few computers in few locations that I use, and with synthing I keep them all in sync, in a way that i can work from any machine at any time and everything is there. The huge numbers come from huge photo/music collections and their management software DBs. And a huge document archive with all kinds of personal/not personal stuff which is actually the smaller portion of those numbers (although an important one).
In terms of reliability it’s decent now. I had some bad data (almost) loss incident about a year ago, but it was a combination of issues, not only syncthing’s fault, luckily i got off-site backups…
For now it’s deeply integrated in my workflow, and I hope it’ll go on like that
However, stuff breaks here and there, and sometimes manual intervention needed to fix things.
As mentioned it’s v.0.x… so no big promises