In reply to:
Get the older one, and add engine monitoring.
The Arnav is superior in several key ways: 2000 hours of engine data storage instead of 35, and terrain awareness/warning. There are ways in which the Avidyne is better, no doubt. But getting the stormscope and skywatch would be a big big plus for me at least.
Yes, the Arnav stores 2000 hours of engine data. It also includes altitude, a feature I miss on the Emax. On the other hand, it’s much easier to dump the data out of the Emax (IMHO), and there are many more tools for looking at that data in clever ways; one of them is feature-rich and free to COPA members, having been written and generously provided by Mike Glazer. I actually look at and use the data I get from the Emax, something I rarely did with Arnav.
The Avidyne doesn’t offer terrain warning, that’s true; but the terrain AWARENESS that is provided is much, much nicer, more intuitive and much more ACCURATE than Arnav’s. Also, a new buyer should be aware that Arnav’s terrain warning needs to be switched on, and takes the form of a visual cue - no audio. It’s not TAWS. Not a slam of Arnav, especially cf. Avidyne which offers no warnings at all; just a clarification.
My most compelling argument is that I have 950 hours behind the Arnav, and about 200 behind the Avidyne. Each has its foibles and advantages relative to the other, but there is simply no way I’d go back.
Agree with your comment on Stormscope and Skywatch, inasmuch as that one depends on the pilot and the mission.