According to JustPingo, there is likely a system update just around the corner; next Tuesday, to be precise (https://twitter.com/justpingo/status/684480415260905473). This makes sense considering all the recently discovered 10.3 exploits, and how long it's been since the last "stability" update. Because recovery mode updates to the latest firmware, you're probably going to want to avoid getting soft bricked after 10.4 is released. I'd personally reccomend you just wait for KTM's release (as would many others on the forum), but if you absolutely insist on risking a brick by using sysupdater, then you should probably try it ASAP. Remember that this is SPECULATION. It wouldn't surprise me if it's correct, but nothing is set in stone, and Nintendo hasn't officially confirmed this in any way. Take this whole thing with a grain of salt. EDIT: To clarify, I'm American. I mean January 12th, not December 1st.