Your concerns were pretty much the same as mine DK. I had a firm stance on not going with anyone that uses any sort of traffic management.
In all honesty though after looking into BT, it became clear that even when 'managed' (and I must stress that only affects to P2P traffic) then I would still be getting a faster speed than any ADSL connection, and in most cases, what Sky fibre offer.
Usenet is not managed on BT infinity - it's not a P2P protocol and maxes out 24/7.
I do under a TB a month, and a lot of that is syncing uploads to online backup services like Dropbox and Gdrive. There are people on the BT forums though that are pulling in insane amounts - literally maxing their connection 24/7 and they've had no issues.