This one just keeps running and running.
NTL contention ratios are simply not directly comparable to BT DSL ones.
The other point I usualy make at this juncture is that despite NTL's marketing that states otherwise, NTL's contention ratios are not guaranteed in any way. They are the 'target' that is aimed for but not always achieved (imo). BT's maximum contention ratios are guaranteed in the contract between BT wholesale and the ISP in question (for IP Stream based DSL products, which are the majority right now).
If you are looking for customer feedback on any UK ISPs I would recommend a visit to
www.net4nowt.co.uk
or
www.adslguide.com