Sorry to say but Hub 3.0 won't necessarily improve your connection, we have got ours last week and its worst than before. now I'm looking to buy TP Link, fed up complaining. Poor wifi range and connection or non at all. Rather spend some money to have adequate data.
The Only advantage with the Hub 3.0 over the SH2AC is that it can Lock more then 8 Downstreams. Each Single Downstream Channel has about 50Mb bandwidth so channel bonding used on DOCSIS 3 and currently the SH2 and 2AC will bond all 8 of its available channels making up about 400Mb of available bandwidth. Up to you if you wish to pay for these extras in the specs. It works well with TP Link Powerline and speed is satisfying even through extension lead. Still doesn't justify Virgins fast fibre broadband via wifi.
Hi I bought the Devolo Powerline plug in system to stretch Virgin's signal through our (very small) house! It works really well, & now we can even get WiFi in the garden. It's a shame that you have to do this, but as you say, less frustration is healthier!