Yes, A&A is very, very good for support. But for the majority of us, we'd hope we would really only need support a couple of times a year at most. You'd be paying more for the quality of service overall, but less options for speed and data usage.
To be fair, 2TB is actually a lot; I don't think I could ever download more than 1TB a month realistically - even on G.fast under normal circumstances. But my issue is they have no 330/50, and the additional £10/m for 20 Mbps more upstream is excessive in my opinion. I would rather pay £59.99/m for 330/50 from a good provider with more than decent support than £75/m for less downstream with a provider with excellent support.
Despite having no external antennas, the XMG3927-B50A does have some decent Wi-Fi speeds. My smartphone is limited to 433 Mbps Wireless AC, but as long as I am in the same room as the router it can pretty much max out the connection (~280 Mbps downstream). Even a couple of rooms away, ~100 Mbps downstream is still possible.