I've had two GPS receivers over the years, most recently one called Ultimate from Emprum. I use Air Nav Pro on my iPad II. When I first got these devices - they worked perfectly. Then they suddenly became erratic. The creator of the navigation software claims that Apple is constantly changing the IOS to make it stop working with external receivers. He claims that he is having to constantly update the program to "work around" Apple-caused problems. He says these problems are the same no matter which receiver you are using - he claims he fields lots and lots of complaints across the industry.
Anyone have good luck with external receivers ? If so, what iPad version, what IOS version, what software, and what receiver combo is working for you ? Also, how long has this combo been trouble-free for you ?