The Air3s is a healthy step up from the Air2s—better features and range.
The "smart RTH" is amazing to watch because it will follow the course it took off from to return (including going under tree cover, for example).
I have spent WAY too much...
I have an Air3s, so I can't directly compare it to an Air3, but the Air3s has an "auto" night mode that is "activated" when in auto exposure mode. I haven't found any indication that it is in this "auto night" mode, but the results speak for...