I've had power poles left connected for six or seven years, in both mobile and stationary application, and haven't seen a problem yet. They were invented for BART (Bay Area Rapid Transit) trains and have been in continuous use on those trains since around 1964. The silver plated contacts are less prone to corrosion problems than most other materials would be, since silver oxide is still conductive. Ohm's law tells us that, if resistance does develop, it will cause more of a problem for high current circuits than for low current.
