I just tried to update my reader from stable version (2015-11-3), but it didn't passed. I must say that KSM and it's WiFi implementation works great, tshering has done great job with it.
As I saw from OTA channel there, there's only difference file (.zsync extension), which should install what's different, alleviating downloading whole package.
But it doesn't work with my version, as I received info on all available servers that there's no new versions (stable or development). I guess I'd need to have download latest nightly, then try again.
Or, we will soon have new nightlies? Well, I'll wait.