There is no setup fee on Cable for new customers really, there used to be an admin fee of £30 or so but many people bypassed that, unless you meet FTTH on BT managed lines?
If you mean Fibre, as in cable BB via Virgin then torrent is just fine, the usage and performance is no different to any other BB connection.
What is different though is your actual speed, you do genuinely get what you're paying for pretty much 100% of the time.
Unless your area is congested ¬_¬ By the time the doublespeed upgrades have completed, the congestion issues should be entirely gone because the upgrade is more than just bumping up speeds, it involves hardware upgrades throughout the country to support the extra loads and make room for all the new stuff.