There are a few other reasons that we've made the change.
First is that Virgin staff seem more enabled to fix issues in a sensible way, particularly when it's beneficial to both them and me. QANTAS staff seem stuck with their rigid policies and never have the power to fix problems, or more importantly avoid problems, even when it's blatantly obvious to all involved that that's what should happen.
As one example, the last QF flight I had booked out of New York was on a Thursday night. On Wednesday, the weather bureau was telling everyone that the biggest snowstorm for years was coming on Thursday. So I rang QANTAS and said "Hey I need to be back in Oz before Monday, can I get out of here tonight, as you won't be flying tomorrow?". Answer was that my flight was still scheduled for tomorrow and so they couldn't do anything about it. I said "have you looked at the weather forecast? You won't by flying and tomorrow you'll be trying to sort this out for hundreds of people so why don't we fix it now?" When I called to ask them on Thu morning, what time I could check in, they said "Oh sorry, your flight was cancelled. We've booked you for Friday night". They hadn't even called to tell me either. By then the weather bureau was saying that Friday was going to be even worse.
On Wednesday, when talking to QANTAS, I said "I don't care which city you send me to tonight, I just need to be out of New York. I'll go anywhere that I can connect to LAX tomorrow". They wouldn't change anything. I said "There's an AA flight tonight at 9PM with 30 free seats". They said "There are no seats on that flight that we can use".
The good part is that I then tried to book with AA directly. They wouldn't take my booking without a US billing address on my credit card and told me to book on the Austalian AA website. It wouldn't take a booking for Wednesday night because it was now Thursday in Australia, even though it was still Wednesday where both the plane and I were... (And Expedia was melting down at the time). I ended up booking myself on a Virgin America flight and got across to LAX ok.
A second big reason is the constant attempt to convert QANTAS into Jetstar. If I wanted to fly Jetstar, I'd book with them. 99.999% of the time, I don't want to. Yet QANTAS keeps replacing routes with Jetstar, and sorry, but I don't want to be there. On Dec 27th, I stood in a Jetstar bagdrop queue in the middle of the day in Melbourne for 2 1/4 hours. I will NEVER do that again. It's pointless having status with QANTAS where I can avoid stupid queues but then be pushed into Jetstar queues instead. A big benefit I've found since moving to Virgin is that at least I can fly with the same airline to mid-sized regional ports like Newcastle, Launceston, etc. and I can still miss the queues, my baggage comes out quickly, etc. etc.