I sent my Spirit 1.0 back to Nestaway for a replacement part after a year as I ran over a rope - they called me to say that they weren't happy with the paint and some corrosion on the bulb and would be replacing the motor which they promptly did. I've had the replacement for 18 months with no sign of corrosion at all. I think he mentioned to me on the phone that there were some early batches that had the problem so it may be worth enquiring?I'd worry a little about longevity, there are signs of corrosion on my Spirit after only one year use (but to be fair, the same can be said of most outboards).
I too would not go back to a petrol outboard. My main reason apart from the quiet and lack of smell is that my wife and daughter have no problems jumping in the boat and pressing go - they didn't feel that way about the petrol.