A reference point, FYI. As I mentioned in the other thread, my '15 SR has been sitting unplugged since early November. I left it at 100% and maybe 2.5 miles back then. A weeks ago rode it for some errands and dropped the SoC to mid-80%, with around 15 miles on the trip meter after that. Stayed at that until yesterday, when I took it out for 30+ miles or so of mixed riding. My objective was to drop the SoC to about 50% and leave it at that for the rest of the winter season. I did not notice any difference in miles per % charge yesterday vs. my normal daily usage in the warmer months (note my battery was probably around 50-60F from sitting in the garage). I was getting about 1 mile per percent drop in charge, which is about the normal average for the way I ride in mixed traffic conditions. Cell balance remained below 4mv at the end of the ride at about 50% SoC (was 3mv at about 85% SoC after having set for a couple of months).
It has been similar last winter, so I see absolutely no reason to keep my bike plugged-in for the winter. Others' situations may vary, but in my non-heated but non-freezing garage (if temperature matters at all), the bike keeps charge just fine off the grid for many months...