That's pretty much the A&A plan that I have, and I think it's worth it for me. This is a case where you get what you pay for, and I both need an excellent level of service (because I depend on my ISP for work) and can afford to pay for it. The equation would be different for other, say, casual users or people on tight budgets.
Also ... IPv6 just works, and I have a /48 assignment.
A&A doesn't supply enough bandwidth for our home (including work from home) use, at least on their pricing page.
On a 5Mbps line, our average monthly usage was about 300G/month, according to router statistics.
Now that we're on BT FTTC at 76Mbps (rate to nearest speedtest.net when there's no contention), I wouldn't like to guess the usage, but I'd estimate over 1TB a month at least. The BT provided router resets its count every 30 minutes or so, and I've not yet put my own routing box in the middle, so I don't know exactly.
Both my GF and I stream a lot of HD video, and I mirror a number of repositories every week. That video is a lot more HD now, and there's far less need to ever turn it off, since it doesn't significantly affect other users.
A more feasible approach would be to combine A&A with BT, and switch depending on reliability vs bulk requirements, but that would require a level of systems administration I'd want to be compensated for.
Also ... IPv6 just works, and I have a /48 assignment.