Thanks for the question. Yes, as you mentioned, the hardware requirements of LOGbinder for SQL Server are not high. I would say a typical server configuration with a few GB of memory and 2-4 cores would be sufficient. Most often our customers run LOGbinder on a virtual machine.
It is not an easy say how many instances could be handled with one LOGbinder installation. It depends on your hardware and on the amount of audit data those SQL Server instances produce. The best would be to do some testing in your environment with a few SQL Server instances and then scale it up.
The biggest bottleneck used to be getting the audit logs from the SQL Server. The more audit data you have, the longer SQL Server takes to provide the requested audit logs. However, the latest version of LOGbinder deals with this situation with purging the processed audit data, so as long as LOGbinder is running, it should not take excessively long to get the audit data from the SQL Server.
As I mentioned above, why not do some testing. If you find any other bottleneck, we would be happy to work with you to see how we can make LOGbinder more efficient for you.