I've only recenlty returned to Oz from a wonderful trip to the UK, flying with Etihad, mostly in first but one leg in business (Abu Dhabi to Manchester) because they don't have a first class cabin on flights to/from Manchester. First was bloody fantastic, to put it mildly and business was good, but it suffered enormously by comparison to first ;-( It was the 'older' cabin in our business leg and we did see the new business when boarding one of our return flights, which did look much nicer (a bit roomier maybe?). We found the business seat a bit cramped but, as I've said, we had just come off a 14 hour flight in first, so anything would have seemed cramped after that.
When we bought our tickets, they were on sale and we paid $8,500 each. I've done a dummy booking, in first all the way (via Heathrow) for August next year and it was only $2000 more (each). I'll happily pay their full price to fly with them again in First.
The service, food, lounges etc were wonderful (wonderful is too tame a word though) in both classes, but if you can consider flying via Heathrow and going in first the whole way, you'll not regret it.