Thanks for your inquiry. Please note 17.9 is monthly stable release of Aspose.Words. It is published on September 7, 2017. It includes all the features/functionality from 17.8 version along with new features/enhancements and bug fixes reported in previous versions.
I am afraid it is difficult to tell you exactly how many customers are using this version in production. However, customers those reported the issues fixed in this version, will be using latest version. You can download and try latest version. Please let us know if you face any issue in this regard.