Success report! I've now had multiple flights with my Ping Buddy connected to my 740, as I described above. All were "local" flights in vicinity of home base, KHWY, which is just outside the DC SFRA. Good reception with the Ping hanging on the canopy bow of my Sonex. USB cable runningdown the bow. Slick.
Very impressed with the traffic display and weather info. Our airspace is fairly congested but I feel like I've got a good chance of avoiding a number of possible mid-airs...of course, we do have a few NORDO and no electric guys fying is same space, but they're almost always flying low and slow. The traffic warnings I receive appear to be legit and fairly accurate (function of the ADSB accuracy).
Whatever I spent on the unit ($135?) was worth it.
When I get my Skyguard installed (low priority, now) I'll have to compare the two...
Cheers
Bill