I have found that Go Cardless has complely transformed my business. It isnt the 'holy grail' of payment collection because it removes a layer of customer interaction, and that can have good and bad consequences for your business.
The good consequences are that for problen payers, the ones that forget, and the ones that are just too busy to remember to make payment its ideal.
The bad consequences is that it removes a layer of customer involvement. As they no longer have to 'interact' with your service by making payment, these customers you would normally have a good working relationship with are at risk of losing a report with you and it makes it easier for them to cancel your service should a problem arise; and in the case of reduced customer involvement in the sale process mitigates any presumed loyalty on both sides. All these switching providers websites are about becouse of the advent of direct debit, and the ease of switching supplier with no need to feel obligated to any particular service.
I dont actively push direct debit. I do offer it as a payment option, i have around 50 people on dd out of nearly 300 customers.
If they become a problem payer, they cab go to dd to continue the service.
I have been using debit and credit card payments through paypal here, that has been amazing for my business as it gives the customer more buying power from you, with credit cards.
My advice is have a range of options. I am discouraging cash now, and making card bacs and dd my preferred option