The fraud I'm worried about isn't from a bona-fida customer, it's from a fraudulent customer.
BadGuy uses your service to sign up for BadGuyDojo, and attaches a stolen bank account. 10 "customers" sign up with stolen credit cards, process payment, and the money is gone along with them. A month or two later the credit card companies come looking to you for the money.
The experience you are talking about wouldn't really jive with the real world scenario which this would be deployed in.
I'm a small business owner and you are my client. You and I have a relationship. You aren't a random BadGuy. The likelihood of you purposefully bouncing a check or committing fraud is next to nil. In this scenario, similar to what Duet is doing (facilitating communications and payments between known vendor-client relationships) the SaaS that processes the payments is pretty safe from fraud.
Now, I would never roll this out on any of our SEO services. When we had credit card payments on the earliest version of Linklicious, we fought over $1200/mo in charge backs from fraud or "fraud." After nearly 3 months of our mailbox filled with chargebacks and complaints, we switched to PayPal and only once did we have an obscene amount of fraud (hundreds of signups from stolen French PayPal accounts) at which point we blocked the country of origin for a week and the problem disappeared.
You have to be intelligent no mater what payment method you chose. There are negatives on both fronts.
BadGuy uses your service to sign up for BadGuyDojo, and attaches a stolen bank account. 10 "customers" sign up with stolen credit cards, process payment, and the money is gone along with them. A month or two later the credit card companies come looking to you for the money.