First, kudos to a very well written article!
I instlled Sentry and after downloading each of the eicar test files, it worked great.
"Be careful not to add folders containing heavily nested folders, as this can eventually lead to slowdowns."
I want to note that the behaviour of the Sentry doesn't appear to recurse subdirectories.
I tested this a few ways:
1) I created a subdirectory called "eicar AV test files" and downloaded all 4 files -> no detection. I dragged the file to the parent directory and it gets immediatley detected.
2) I tried to reconfigure and relaunch the Sentry thinking it might recurse on reconfiguration but nope - same behaviour.
This is just a heads up - because of the active menu bar icon, it's really easy to tell whether a directory is being monitored!