I have to say I am not a fan of BT kit. If you read the BT forums, they have had quite a number of problems with the kit. What is putting me off is the BT refusal to give decent technical advice so you can decide for yourself what you need.
The other complication is that the phone comes in at avery inconvenient point and I have laid wiring so that I can have the ADSL router in my dining room at the opposite corner of the house where the phone comes in. That wiring will need to be replaced with their data extension kit as the existing wires cannot take the high speed data transmissions.
It is beginning to look like its too much trouble to bother especially when I can't work out costs etc beforehand - which is unfortunate.