Our Shipmate stove is going strong after heavy use for 33 years, about half of that full-time, everyday use. It doesn't have thermocouples on the top burners. I don't think that's a problem unless you leave a pot on the burner unattended -- not a good idea on a boat
It's nothing but a heavily built stainless steel
box, so if you want to replace the top burners with modern ones, it should be well within the capability of the average do-it-yourself sailor.