I have one and was installed on a Corsair 31R. I only install it when we the boat is out sailing. Last used it for a 400 mile run. It stopped working so I did have to send it back once so far. Took awhile to arrange and ship from the middle of the pacific. Calypso said it was bad part from a supplier.
I have a new one they sent back and it will be driving the auto helm on the next trip in mid-October. Will post how that goes.
As for accuracy it is very good. I ran both sticking out the moon roof of the car on long extension rod.
Just need to see the durability at sea be