In stronger winds the autopilot becomes less and less efficient, and it certainly will have a hefty appetite for precious electricity. As conditions deteriorate most autopilots are simply not fast enough to handle steering effectively. Perhaps part of the lure of the autopilot is the urge of the modern sailor to feel he or she is using the latest in technology. However, saltwater and electricity do not match, and when saltwater wins the windvane will soon prove that there is no need to reinvent the wheel. If it seems old-fashioned it might be because it is.
Sailing is also old-fashioned.
Let's face it, there is not really anything modern about sailing, the best way going to windward is in a 747.