Don:
Correct. There is a lag, but still usefull glide info.
The free app called BASEline has the glide ratio ability. I've tried it and after you find your best glide speed it does settle down.
I too have the Dynon D10. I have done some glide tests with a dead engine at a local dry lake.
I have a paper tablet on my knee board with two columns. One is IAS and the other is descent rate.
With the engine off I set different speeds while noting descent rates.
One needs to factor in wind speed and direction. This info is available on the Dynon D10.
At your best glide ratio you would obviously not glide as far in a headwind and a tailwind will take you farther.
As an extreme example: My aircraft stalls at 35 MPH so in a 40 MPH head wind, at an IAS of 40 MPH, at my best glide speed I would be descending almost vertically. So to get more distance we need to consult our Dynon and turn to get the wind off the tail to get any distance to reach a safe laning spot.
Upper winds is another reason why the Glide Ring would be unreliable.
That said, flying at the best glide ratio would give more endurance allowing more time to call in an emergency.
I guess the best solution for those of us with Dynon would be for that company to provide a glide ratio. I will suggest it to them, but doubt it will have any effect unless they got many requests.
John M