Very peeved off ( i'm holding back what i really think ) this has happened , as I specifically booked the A330 this Sat for a A330 "taster" trip. Just contemplating whether to go at all now.
Recently did SYD-PER and return on the A330 (both in J). The outbound was on the newer seats, and the return was on the older ex-EK seats.
There's a big difference in experience, IMHO.
If you're going SYD-MEL, i.e., a 1-hour 'taster' flight, I wouldn't bother if it's an ex-EK aircraft. It may give a bad impression and do the newer A330 aircrafts an injustice.
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Which is why the A330's should be exactly the same in terms of fit-out
Consistency is key!