I'm one of the many users of FraudLabs Pro. I'm very happy to use their service in screening fraud orders and hope it can be integrated into the WHMCS core instead of an independent module that could be broken when we upgrade. Blesta and ClientExec have integrated it into their fraud module core. It has free Micro plan that really help us when we are still a small business.
You can find many reviews in the forums that are supporting the usage of FraudLabs Pro.http://www.webhostingtalk.com/showthread.php?t=1661883
More than one anti-fraud
It would be nice to use multiple anti-fraud at the same time. Let everyone say "yes" so that the order is accepted automatically.The various anti-fraud have different advantages. Some consider the ip, other phone number, other numbers of credit cards. It would be nice to take advantage of each!