Dedicated Business Fibre is as the name states, it is dedicated to your business, the line speed your business take is the line speed it gets. This is normally a synchronous line that boasts full downloads and uploads at the same speeds, so if you have a 100MB line it would be 100MB on downloads and 100MB on uploads. There is normally no shaping, throttling or sharing of the bandwidth, we like to explain this as having your own lane on the highway and taking your Ferrari full speed and not sharing the lane at all.
This is the glory boy of all of the internet but yes, it comes with a price. This is not always for all businesses but when you see the light, your business will never go back. Your business will be able to run multiple tasks at the same time, your users will be able to stream from many devices, have a multitude of voice call and video conferencing, download of emails and documents and all while your business carries on going with no one even noticing the amount of data being sent and received.