Thank you for the quick reply.  I really appreciate that.

I actually just tried Milo based on the information provided in this thread.  The problem with that service is even when using "Guest Checkout" your client will have to essentially set up a profile to use the service.  It's not as simple as just entering credit card or bank details.  They have to enter a bunch of information.  It's much more time consuming, which creates an inconvenience barrier to paying invoices.  Is there another service that you recommend that streamlines the process for paying invoices?