Re: ipad as instrumentation...
I have pretty much decided to do just iNavx with a bluetooth gps puck and leave it at that. It will be cheaper and have a larger screen than a chartplotter in a my price range. The multiplexer option was too involved and $$$ considering that I would have to get all new sending units.
It looked cool but I am not willing to invest more than the cost of the boat in instrumentation...LOL