I used it about 2 yrs. Was it worth it, for me no. I store the boat on it's trailer so water in the bilge is not an issue. It did tell m every time the battery was low and when in for service if the dealer disconnected it.
The Geo fencing worked well. I would forget to turn it off and about 5 minutes after I left the storage facility with the boat in tow I received a call. Now the boat is in covered storage. The unit, while still on, was trying to "check in" and was draining my battery quickly. like a cell phone trying to communicate with a tower but can't, the battery gets used quickly. Now that I've actually turned it off, the battery is good for well over two weeks.
As to it's worth to you, you will have to decide. It does work and the wife liked being able to see where I was when out alone by using the web to have the boat display itself on a map. We did also have the seakey system through he web interface send emails to friends when we were on a one week cruise to verify that we actually arrived and nothing was amiss.
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Jvalich
http://www.badcock.com'04 FW 288 Vista "Mental Floss"