Although not directed to myself this is a very good question (#4 message).
I myself I have just signed up for a Full Fibre 900 service having been on a 80/20 FTTC via Glide business.
Truth be told the 80/20 service it's fine and I do not have any buffering with multiple streaming devices and two people working from home. Glide has provided a consistently reliable service but it isn't cheap.
BT's 900 service is faster and cheaper than what I'm currently paying, but I don't need all of that speed.
Really only needed (useful) for downloading large files