I finally took the plunge and purchased an Aura after Humax dangled the £50 off carrot and I have to say I am very impressed so far.
The speed difference and generally useability after my 4000 is like night and day, I am still getting used to pressing a button and the box responding instantly. It is also incredibly quiet. I read in one of the posts that the Aura has a fan, but I cannot see any evidence of that looking through all the ventilation holes. If it has, I haven't heard it.
I have it connected to my Samsung TV and home cinema and the Humax seems to talk to it and the TV and Home Cinema turn off when I turn off the humax. It plays programs that are 5.1 correctly. As I have installed Plex onto it I have been able to lose my Apple TV as that is all I used on it.
Not experienced any signal break up so far or any other little quirks, this is one of the main reasons I did not jump into one sooner as that seems to be quite an issue with some people.
A couple of observations:
When using the jump to date feature in the guide, it would be good if the pop up the with dates went horizontal rather than vertical as that seems a more natural movement to me. Also, when you go back to jump to another date, the cursor is back at the top of the list of dates instead of staying where it was, so you have to scroll down past the date you are on to get to the next day.
I have set my unit up to go into deep sleep after an hour of going to standby and for the standby light to go off. I notice that it seems if I put the box in standby myself the light will stay on even after the 1 hour, but if it wakes for a timer and then puts itself to sleep the light goes out. Having said that I noticed the morning that the light was out and there were no recordings after I put the box to sleep, so maybe I have got that wrong.
Last thing is the Plex App seems to default all the programs to stereo instead of 5.1, so I had to select the 5.1 audio streams on all of my programs manually. I couldn't see a setting to change this as a default on the App nor in the server on my Mac.
All in all, I couldn't be happier and I would say, if you are sitting on the fence wondering should I or shouldn't I, then I would say go for it.