Rich,
I agree, a Wi-Fi antenna option would be great and it something we are look into. We've added the rudimentary support for Wi-Fi antenna's like through a Clarity ADS-B or SkyRadar, however it is not completely developed just yet. Our hopes are to use them as a redundant GPS source and let the iFly choose which has the better signal.
There are not to many Wi-Fi GPS antennas, Garmin, Dual, Bad Elf and others are catering to the iPad and tablet trend using Bluetooth. While the majority of others are using Wi-Fi as it offers more powerful signal and a more seamless handshake. Most Bluetooth units are inconsistent and need to be connected to if they are separated. Wi-Fi just automatically connects better. It should be an interesting play out here.