The Etihad scheme allows you to buy stuff from their online ‘mall’ or better still cash in on a prepaid virtual credit card called Pointspay to buy what you want. The rates apparently fluctuate but four of us return to Oz in economy netted me just over £200 that I spent at JL, Amazon etc.
Of course swapping for cash gets you less but the online mall prices are higher than the high st and assuming you don’t plan on accumulating miles for further travel than effectively you’ve got something for nothing.
As an airline Etihad is excellent with flights from more than just Heathrow. Connections in Dubai are pretty painless as it’s just a classic megahub airport built where there’s plenty of space. I can’t imagine getting to Auckland will be hard but it might require two stops as ISTR only Air NZ do a single stop (LA or Singapore).
If it’s only worth 50 quid to spend online I’d only considering it all other things being equal.