I use my ultegra DI2 equipped bike all through the winter and for commuting, only problem Ihad, was my battery started draining quickly. I thought it was water in the connections, but it turned out it was the battery indicator that was faulty, which is a known fault. I replaced it and no problems since. When I took it to my LBS for them to run the diagnostics on it, they said they had never seen DI2 used for commuting or one that was so dirty, but it has done about 6k in winter conditions. Some of the connections are getting a bit iffy. They do not connect with a positive click, but work without any problem, so I just dont disconnext them to clean it anymore. Just treat it like you would any other groupset.