A couple of additional thoughts.. I've tested a few external GPS units with the Latitude 10 and ArcPad via the one USB port on the device and Bluetooth, and they work great.
As I see it, this is not an issue with traditional GPS devices but rather one associated with the way newer devices (tablets, phones, etc) have integrated gps into their hardware.
To me, it seems to be one of two solutions: a) Dell or Broadcom needs to provide a user-level device driver (UMDF) that will allow sensor api-dependent gps receivers to pass their NMEA stream to a port, so these integrated GNSS or GPS devices will work as other, more traditional (ie.d, port-based) devices or b) ArcPad needs to be able to look for devices on ports and the sensor API. Michael Chourdakis' TurboGPS has a good example of how this might work under it's GPS setup where can set the application up to use either com ports or the sensor API. For me , that's just another (albeit great) piece of software...