I paid for an I-class LHR-DXB a few months ago and am fairly sure it was nowhere near as expensive as quoted above.

One thing to note about BA coming back is that it's a sleeper service but you don't get pre-flight dining in the lounge.

I seem to recall reading somewhere that EK has special security arrangements at DXB so that might make the airport experience better on EK ? (I've never flown EK.)