re: First boat: Cal 2-27, Pearson 28 or Islander 28?
I think it is great that you are being something of an inovator with the electric power plans, but would urge some caution moving forward. You will be using the boat in an area known for challenging sailing conditions and big tides. I think most new sailors end up using their motors more than they think they will, it was certainly true for me. As it turns out sailing in fog, against tides, or into a big headwind and seas takes a lot experience. Unless you have a small boat on a lake (not the Great Lakes), having a reliable motor means more than just getting in and out of the marina.
I have no personal experience with electric propulsion, but do note that most estimates of run time on batteries are under ideal conditions. Your sailing venue is kind of the oposite of that. I also sail in an area with tides and have experienced huge variability of transit times based on conditions. This summer we were heading home on a course that under ideal conditions would have taken 30-40 mins. The weather, forcast to be wet but calm, went bad, with wind and chop right on the nose, we got slowed down and ended up hitting the ebb tide just wrong, and were making zero headway under sail. The resulting motor home took about 2 hours and burned a lot of desiel, using about 50% more throttle to go 1/2 the speed compared to good conditions. Knowing that my tank still contained many hours of extra energy to get home was a big help.
Others will point out that many sailors have traveled the world with no motor at all. This works if you have great boat skills, or no time constraints. In the situation above we could have turned tail and anchored in the lee of the weather and been safe. By the time the tide turned and the weather settled down it would have been after dark.
All said and done I will follow your expereince with interest, please keep posting. In the end my prediction is that you will end up keeping the ourboard, if it works ok, even if the electric drive works out too, kind of like the Chevy Volt. Having 2 auxillary systems is ok, but might be a bit crowded on a 27 foot boat.