I'm on the fastest one, the 76. I have found that latency is a little bit higher than Plusnet but still under 20ms. On one day I am sure that speed dropped during peak time, I haven't monitored that too closely though.
Latency is more stable than Plusnet, which had latency spikes even when the connection was being used lightly.
All in all I'm glad I made the move.
BT -> Zen -> F2S -> Bulldog -> Be* -> BT Infinity 2 -> Plusnet Unlimited Fibre Extra -> Vodafone 76
Say it with flowers, give her a Triffid