Invoicing with Xero, QuickBooks is great, but...
... they primarily focus on basic invoicing functionality such as sending/receiving invoices and basic payments.
Risk assessment - Do you have a policy in place? Is it automated?
Financing options - Do you know your options or need to apply and process separately each time?
Invoice insurance - Do you have protection from non-payment on each invoice?
Aging/Bad debt - Do you manage it internally? How do you deal with bad debt?