The iFly 720 supports WiFi and Serial connections to ADS-B. The Dual XGPS-170 is Bluetooth, therefore it won't work as an option for the 720. It will work with the iFly GPS app for iPad or Android though. We've looked at BT dongles, but they will not work with our OS. We've also asked Dual to provide us with a USB driver so we could support a wired connection, they don't support our OS.
You might check out the PathFinder from Flight Data Systems, it's WiFi and they have a Portable and Remote mount option. It's very affordable at about $549. Hope this helps.