We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
#1489 - PayPal IPN "Recurring billing agreement cancelled" responded to with HTTP 500
I have made a number of changes, regarding cancellation, and better tolerance regarding mismatches with configured prices (as subscriptions can get out of sync, but once initiated, shouldn't fail or return errors).
Looking into it :).
(There's another tracker issue I need to get back to you on, will do soon)