I have been using the sup8dof for a while now & it is a great module and perfect for many marine applications.
However it would be good to also output the compass heading as a separate NMEAsentence eg $xxHDM (or HDT etc) as many autopilots and navigation systems expect this & not all can extract from the RMC sentence. The feature of using the GPS heading while moving is good also (but would be nice to have the threshold speed configurable.
I have had some difficulty being able to extract the barometric pressure from the current generic sensor sentence. What is the possibility of using the $xxMDA sentence for this.