Pelagic is great from all I've heard, and Brian Boschma is a hands-on guy with many sea miles on his Olson 34.
His interest was in tiller-steered racing boats, and in gear that could make the necessary corrections even under spinnaker in rough conditions. Off-shelf products just can't do it, and the power requirements in heavy conditions are high-- 6 amps plus. He solved the problems.
But for casual sailing with a wheel, I still say you can't beat a $1500 Raymarine wheel pilot. It's good up to the first reef, in calm seas, and allows shorthanders to hoist sail, or go below for a Coke, or motor for hours free from tyranny of the helm. Installation is fairly easy, and yields push-button course changes and tacking.
I say this because wheel pilots are widely condemned for not doing what they can't. Sailing Uma complained that they failed in a Transatlantic. Delivery crews beef that 10-year-old (worn out) Raymarines can't hold a course. Others mutter than they turn themselves off whenever the wind comes up.
Even for a 16,000-pound E38, the EV-100 works marvelously well within its limitations. Sails must be set for a balanced helm, which in whitecaps means reduced sail--a necessity for all forms of self-steering. Everybody should have auto steering, in my opinion, and a cheap wheel pilot is the easiest way to get it.
The Raymarine is enough for most of us, and changes the whole business of casual daysailing and cruising. Video on setup and operation
here.