I got a second wheel drive unit as I am not sure of the ruggedness of the drive unit itself. I have already replaced the
motor (a small 555 unit - I think worth about $10) and have done a belt (which cost about $120 to replace I think).
In the end I was worried enough about the drive unit to install Pypilot as well as the Raymarine. So I have a spare drive, a drive on the wheel I don't use and the PyPilot drive I do. So keep an eye out for a spare drive, we used it when we did a belt when
offshore and swapped the units over.
I don't have a rudder angle unit as it is hard to get one to fit our cat. The system worked okay and steered us for a few thousand coastal miles.
cheers
Phil