So, after the weekend, this is what I found: BTSync is on only two OSX boxes, running the latest version. Syncing only one folder with relay, tracker and DHT off. My machine was relatively quiet, with only one attempted connection to an IP that resolved to Brazil. The other machine, which happens to be running uTorrent, attempted nearly 5300 connections. This might just be DHT tables, but it's curious that the machine running uTorrent has attempted so many connections as opposed to the other machine (1). I'll take a look at setting up pre-designated hosts and see how that goes.