Welcome to AFF
@michaeltprice !
We can't give individual financial advice here; only you can decide whether it's "worth it".
What experienced AFFers will tell you, though, is that if you want to accumulate frequent flyer points, the way to best do so is via a "Flexible points currency" rather than throwing all your eggs in one basket of one particular FF programme such as Qantas FF. (See article below)
As for American Express, it's my primary card. I would dispute the assertion that AmEx "typically charges more" -- occasionally its surcharges are higher than Visa and Mastercard, lots of times the surcharge is exactly the same, and lots of times there's no surcharge at all.
Yes, you'll also need a Visa or Mastercard for those vendors that don't accept AmEx. But I personally find that the points earning potential of AmEx, along with the other perks that come with the card, make it worth it.
But is it right for you? You need to do your own research and compare what you find with your own spending patterns, as well as what you want to use your points for. If you want to use frequent flyer points to fly domestically within Australia or short-haul to places like NZ, you may in fact find that Qantas FF is the way to go.
Credit card rewards programs offer flexible points currencies that you can transfer to whichever airline has the best deal when you book.
www.australianfrequentflyer.com.au