Dear Dynon Support,
Bingo, you've hit the nail on the head! You've stated that you need a DG with almost zero drift to make this work. The reality is that virtually all light aircraft currently operating within the region of compass unreliability are currently using their cheapo panel-mounted DG, be it electric or vacuum operated. Pilots set the DG to runway heading, then fly off into the wild blue yonder based on the heading reference provided by their trusty DG. And as for GPS, well, I've had more GPS receivers fail than any human should, so I want something to act as a backup. A grid-reference DG is a great way to provide this safety net.
Gyros precess - that's a given. Even the expensive ones precess. The 'gold standard' C-12 compass system used in military and commercial aircraft likewise drift. This is a given, a known. Anybody who flies grid has to make an attempt to calibrate the drift rate and use that drift rate to manually correct the indicated heading. Believe me, I've done this more times than I care to admit. Fly the airplane down south where magnetic compass can be somewhat relied upon, and set 'grid', then fly for an hour, and re-select "magnetic". This allows one to see how many degrees the gyro has drifted within a specific time. In this manner we can calibrate the precession out of our navigation equation.
Now over to Dynon. How much does the solid state heading gyro precess in terms of degrees per hour, worst case? If it's not absolutely horrible (ie less than 15 degrees per hour), there's no reason why a grid reference function shouldn't be offered. Clear wording of the pilot's guide would have to be used to ensure people understand how to use it, as has always been the case. And a clear indication of 'grid mode' on the EFIS would be required. Might I suggest placing the word "GRID" beside the heading reading?
In all honesty, this is a function which is fairly easy to implement. I find it difficult to believe that Dynon, who's concentration seems to be on packing huge functionality into small packages, hasn't already implemented a DG function.
(Just as an aside. For those of us who do wander around in the north it's an incredibly good feeling to have a backup system. GPS is a godsent device for polar navigators, but those receivers do fail. In that featureless terrain where maps are of no use whatsover, having a DG to guide you back home is very comforting, because it's no fun spending a night out on the tundra!)
Thanks for your consideration!
Mark.