Last things first: on my phone I only run syncthing "on demand", so I can't actually answer your question. Maybe someone else can chime in? From the little I've brushed up against the issue you're referring to, I think there's a way to have it not get killed, but it seems like it might be a little bit of a hassle.
No shortage of reading if you have the time! I'm quite happy to be running just the "standard" package (although, yeah, I should've pointed out that I don't run in continuously on my phone...)