Tim,
I have put the PowerExpander in both my 35% planes. First, I don't think your first setup will quite work. The BatShare introduces a 0.5V drop so you will not get the output voltage of your regulators to your receiver if you put a BatShare in between. Also, regulators in general do not play well together when you connect their outputs together. One will try to handle most of the load and you will consequently drain one battery quicker than the other. If you want to go with redudant batteries then you should use the Fromeco batteries with standard DSC switches and the Batshare and an Adjustable Regulator. If you want to use the PowerExpander then you would use the same setup but change the BatShare to a BatShareHD and the Adjustable Regulator to an Adjustable RegulatorHD. This will plug directly into the PowerExpander. On the PowerExpander page there is a link to typical setups. This may help explain things. Please let me know if I can help further.