Hi again,
I was also thinking of going for the previous generation 810 or 1010. Airplay i wasn't too fussed about as i have an Apple TV. 4K compatibility, although not so relevant now, may well be in the next 2 years.
Also, if you can, its worth hearing the 810 and see what you think. From what i have read though the previous gen Yamaha's are slightly different in their sound to what the new receivers are like.
I'm not going to be replacing my kit for a wee while, so it made more sense to get kit that was as future proof as possible.
Regards