Case - I know what you mean re: TM ducer. A buddy of mine has a Garmin that kept flipping off. What a pain in the butt, it finally ripped off one time when we didn't notice.
Thru hull installation is causing some anxiety though, the high speed fairing block is big $$, cut once & cut right as well as the fact that the wiring need to run from the bilge, up a leg in the t-top and into my electronic box. Why don't they provide a connection you can remove/ replace yourself?