I got Infinity last year with HH3, engineer had to fit a new face plate. The in-laws got infinity a few months ago with HH5 and it was plug and play effectively.
I get 55Mbps wired to HH3 but only 40-45Mbps on wifi iPhone/iPad. Powerline sees around 30Mbps so I may need to upgrade that. I think I've had 2 minor issues in 18 months which has resulted in internet lost for literally 5 minutes each time. BT customer services have been spot on for me with upgrades/renewals and queries. Can't fault them.
I'm thinking of uprating my router to get full speed via wifi (not that it'll make any real world difference tbh).
Also worth noting, BT Wifi uses around 10% of line speeds from what I've read (if you're signed up, as default you are). Since my log in details don't work, I'm considering removing my access to hopefully squeeze that little extra out of my BB lol