Old thread, but when I tried the stratux with AHRS board, it seemed to work just fine. AHRS board is only, what, $15?
I don't know how this project is coming along, but if you have the Stratus3 and need it set to Open Mode, perhaps you could talk a nearby pilot into loading the Horizon app on their iDevice and switching the Stratus3 to Open Mode. It *should* not need to be set again.
As of yet, we have not fixed this bug yet, but intend on having it fixed for 10.4 due. Release date is still TBD.