We use this app for about half of our online store shipping rate calculations (all calculations coming from our public store). We have found it quite attainable to create scenarios that match the scenarios that we are doing in other systems we use for rate calculations (including our ERP and private stores). The only this we wish could be maintained would be all the details of the shipments it has generated rates for and then to be able to query the app via API to suck all this information back in to our systems.