I fitted one of the RIBS with the 12" plotter and DSC set back in April 2006, I was so impressed with the plotter I promptly went and bought another one for one of the yachts.
Having said that I have returned the plotter (from the RIB) once already as it had both steamed up and four of the five menu buttons below the screen had ceased to work. The plotter aboard the yacht has been perfect but is of courser protected from the elements. There was no problem getting a replacment from the dealer.
I've also got 4 of their hand helds and have found them to be tough and durable.
Over all I like the kit but would be intrested if any other open boat owners have had a problem with the 12" plotter. With new boats on their way for next year, I would like to fit more of the same but can not afford problems.