Hello from the future!
I know this is an old post but I am also looking for an answer to this. I use podtrac also and have almost the exact same numbers you have posted here though a few less rss subs. Why the discrepancy and honestly what exactly is an rss subscriber?
We have been using www.podtrac.com to measure our analytics, and so far it has been quite helpful both in tracking the downloads/listens on our Squarespace website itself as well as the various streaming services.