I have used the cig plug for an MP3 player and Cell Phone charger since day one! No problems so far, have not used it with the GPS yet, was unaware about any problems using the plug!

I think the MP3 is the reason I don't hear any ticks, rattles or noise from the engine. I run with it off the other day and imagined or heard all kinds of ticks and noise! Best fix for a noisy engine!

 

True, I have a Garmin 660 and when not using the GPS it has a cover that completely covers the docking pins...
Never had any issues with it.

When I had my Garmin 550, I cut the connecting wires and installed a battery tender style plug ( purchased at Car Quest) between the cut. This allowed two things, one I could remove the GPS mount for safety and weather protection, plus I installed another connection on my 2ND bike ( sold now) and could switch the GPS from bike to bike without having to wire it up...worked real good.

 

My 550 GPS mount also has a cover for the shoe. I had 2 of the covers break and I lost them. I now carry an extra cover in case it happens again.