This is a great product for the UK. Sadly, unless they get acquired quickly, they'll get destroyed by fraud. The Direct Debit Guarantee means that as the account-holder, I can tell the bank to give me my money back immediately, with no reason. So a fraudster will make some charges, run away with the money and GoCardless will be left holding the full liability.
This is one of the reasons that it's so painful to be allowed to process Direct Debit transactions in the UK.
We've recently launched an Direct Debit facility and faced these exact problems. Luckily our DD provider works with some huge companies and so is already insured against any "indemnity claims". This insurance is reflected in our transaction fees though.
This is one of the reasons that it's so painful to be allowed to process Direct Debit transactions in the UK.