The system allows me to keep track all my invoices in one place which makes it easier for customers that receive payments from multiple companies at once (or even several times per month).
It also helps with accounting purposes because you can see how much money each customer owes or if they owe anything back yet! Not really any downsides but sometimes when sending emails through this program there are problems getting them out into other programs like outlook so we have had some issues communicating via email between clients who use both systems simultaneously. This would be helpful especially during tax time where keeping up records becomes more difficult than usual due our being required by law send us quarterly returns etc..