For what it's worth, the bad elf plugs directly into the ipad in a very loose, insecure way, whereas the 150A uses bluetooth. I had no trouble getting a gps signal in my Cirrus with either device, however, the bad elf did not receive a thing in the 75 I flew in as pax from JFK>SJC>JFK (haven't tried the 150A in a large plane yet). I also note that trying to keep track of the tiny lil bad elf device (which did not seem to enjoy being connected to the ipad) drove me batsh:t and I switched to the 150A.