I evaluated both units when I purchased a new wheel pilot a couple years ago. The Simrad had a larger motor, drew less current, had a higher speed than the AH 4000. (Advantage Simrad) I also know a number of owners that have experienced problems with the control head micros-switches failing on the Autohelm unit. (Advantage Simrad) The housing on the Simrad is manufactured out of aluminum, the Raymarine
out of plastic. (Advantage Simrad) The Simrad had fuzzy logic software at the time, the Raymaine did not although they may have it today. (Advantage Simrad at the time) The installation for the Simrad was very simple as the fluxgate is on the control head, the Raymaine unit required that the fluxgate be mounted in the bilge area. (Advantage Simrad) The only negative the Simrad unit has is that you must reach around the wheel to make course corrections, reaching through the wheel could result in a pinched pinky. (Advantage Raymarine
) although I reach through the spokes anyway, don''t try this at home,I am a professional.