Simon 5 is coming soon!
Simon version 5 is currently in beta testing. It is a massive update, introducing a much-requested feature: syncing the Simon data between multiple Macs, plus a Simon Status service, a Link Checker filter, improved Find filter, iMessage and Speak Error notifiers, a new app icon, and much more.
Important: please note that Simon 5 requires a minimum of macOS 10.12 (Sierra), and will be a paid upgrade from Simon 4 after the beta. Purchasers since September 1, 2020 automatically get a version 5 license (that also works in previous versions).
Re: Change being triggered at every check?
You can use the Filter feature to eliminate unwanted changes — either by using the Block filter to specify start and end text to restrict the output to only the HTML between those two, or a Find filter for more complex manipulation (e.g. a regular expression to remove the offending text from the output).
Tests that don't report changes might be lacking a filter to detect changes.
Simon loads web pages in the same way a browser would, so it would be tracked by analytic tools. You can check a special page if you just want to check the up-state of the web server, and don't want to trigger analytics or usage logging.