Golly, Pete, you write as though you like your airplane.
I'm with you on the D-10A (with the EDC-10). The heading indication is about worthless for serious instrument flying: leads, lags, it won't calibrate out some errors, and a horizontal tape for heading is, in my not so humble opinion, goofy (so please to notice the new, improved, ersatz DG is a compass rose format). I, too, use the GPS's DG display for precise turns and heading confirmation (then there's the crosswind factor! Argh). I hope that Dynon does a better job with the D100 HSI; a fancier picture doesn't make bad information good.
What do I like? Real time TAS and density altitude. Yeah! No more cranking the OAT into the ASI, and twirling the prayer wheel for DA. (This is almost as good as real time ground speed that GPS brought to the party.) Life cycle cost of a MEMS instrument is sure to be lower than overhauling mechanical gyros liquified by vibration. And it brings a lot of information together into one box that, ahem, backs up the primary 3 1/8, instantly interpreted, clearly observable, distributed failure risk, single purpose analog guages.
John Siebold
-7 and -7
Old, blind, and I don't like TV any better in the cockpit than in the living room.