My brother has a Gibsea 372 with an ST4000 on the wheel. It gave good service until on day he was sailing under 'Genny' alone. Not realising that the unbalanced sail plan on a broadreach was putting such a load on the rudder he was taken by surprise when the Wheelpilot 'exploded/disintegrated' sending a shower of little wheels and plastic bits over the cockpit, never to work again.
It's since been replaced with another ST4000 and is again giving good service.
I guess the secret is not to overload it and it will be fine.
As for not giving an accurate coarse, it probably just requires it's 'settings' altered. Our own Raymarine autopilot has a 'power saving' mode that only makes infrequent course changes to reduce the battery drain.
Incidentally our B38 has a 'Type 1' Raymarine actuator arm fitted to a quadrant on the rudder stock, this does look like a better arrangement..............Bill