Hi Genghis,
I got a Aera 500 on lone/trail a few months back, quite liked it, and decided to keep it. At the time, I had not researched all of the features of the 500 series relative to each other. That said, I was not looking for all the fancy features anyway, so it worked out well.
The only aviation feature I wish it had (which I suppose is reserved for the pricier Garmins), is that I came to like on the G1000, where a magenta line shows you where you will be in one minute, all things unchanged. The manual lead me to expect this, and it is not available. Other than that, and the references to verbal warnings into grass strips, I am entirely happy with the avaiation side.
The automotive side has presented a couple of dissapointments. I have just completed a 6700 km driving trip in the United States, and used it the whole way. In some cases, the data base did not account for changes in routings and detours. The result was that when I could not maintain the prescribed route, and GPS took long enough recalculating that I had already missed the next turn, before the GPS had computed it. with expressway on and off ramps close toggether, it was a problem a few times. Also, even with the map selected with the most detail, zooming out will cause smaller roads to no longer be displayed. This can lead to driving across an empty white display, if the local area is not too populated!
Also, the English woman who hides inside there, was commanded to be silent very early on. She was not very patient, and has bizaar pronunciation for some of the local roads. My first venture onto our local "Highway 11" was presented to me as: " Your are now entering H...W...Y...one...one". Unfortunaely, when you command her silence, it also takes away the speaker audio for the bluetooth phone. Someone will phone, and when you answer, they hear the string of profanity you speak, as you try to get the mute off, so you can hear them. Hearing their laughter when you finally do un mute, can be funny though.
All in all, I am very happy with it though, and would highly recommend it. You never know whe you might have to find your way to some place like Haselmere!
Cheers, Jim