The reply made by our team member on wordpress.org, specifically answers all concerns brought up in the article you referenced. If this evidence is not enough, then we recommend that you stress test the plugin yourself on your own server?
The plugin is free, the import feature is free, and we give away test data for free. Pointing to someone else running 1.5 million records, does not prove your server can run the same. We strongly suggest that you setup 1.5 million records on your own server before you spend any money on BePro Listings.
Once you have tested the free product and you are happy with the performance, then we can help you with customization and expansion.
BePro Software Team