Matt: I have a similar setup without your blackbox  and that box is such a great idea.  I immediately thought of building one until you indicated how much time went into it.   I think you have a great deal for someone who does not yet have Chartcase and a tablet and Wxworx receiver.  I thought your Wxworx price was a little low since a new Bluetooth box is $700+ and USB box is almost $600.    I have the earlier LE1400 tablet, Chartcase, WxWorx bluetooth, GPS and you are right, you can use the tablet as a Windows machine and it does a good job on the road not to mention flight planning, internet access, VFR/IFR/Terminal/Approach charts and moving map.  The Chartcase people will transfer a subscription so this is a good opportunity for anyone who wants a full IFR and VFR setup.  If I didn't have all that stuff already I'd take it.  If anyone does take it, give yourself a lot of days to learn and fly with the setup.  It is rich in capability.   Good luck, I think it is a steal.