What is you main reason for this split? Is it because of too big project (slowness), maintainability or something else?
You need to move all the entities to a new project? So whole set of data related to non-commercial/commercial data? Including links between entities, attachments, favorites, etc? Did I get it right?
In this case I would consider project copy (full) and then delete unnecessary data. The problem is links between entities. Example if you have link Test Case-Test Instances-Runs-Defect, QC normal delete doesn’t work for all the use cases. But it would be much easier to make a tool for delete operations than whole copy. We have made a tool which allow you to move Test Lab data from one project to another. This is for archive purposes when your project size will grow too big.