I'm still using an old Tiller Master on my 30' Tartan. The main circuit board has been replaced once - when it dies, I have a spare unit (eBay).
Off the wind with beam or following seas, it doesn't hack it. But that's when hand steering is fun. On the wind it probably steers better than I do, and under power it's a blessing. I'd love to try a servo wind vane, but that's big bucks.