I've been running with this contact slider mod for a few weeks now, or around 5 mows, 13 dock sessions. I cleaned them when I first installed them and I haven't cleaned them since - they still look just as clean as the day I installed them.
If you don't want to risk your warranty, this is proving to be the next best solution to avoid having to clean the contacts all the time. The person who designed them has the project here. If you don't have access to a 3D printer then you might be able to find a local printing service that can do it for you - just note that you need to print two of the same parts for a full kit, and you'll need to source the appropriate springs