Well, for what it's worth, I think ung has a point. I buy biz class from EK to travel ON THE A380 and spend 3-4 hours standing at the bar.
On the London route you do (almost always) pay extra to fly the A380 so (IMHO) they should compensate you if they swap out the aircraft. Good luck with that however, ung, as I expect you to get nowhere with EK on this issue.
I also have a problem with them promising lie flats on the 777 and then swapping the a/c at the last minute to the recliners - I complained to them about this when it happened on both sectors to London return last year and they politely told me to get lost.
I've been enjoying BA's upper deck for the last year but EK's sale prices were too good to miss...