I found this thread while searching for leads on a new issue that has come up since our MX upgraded from 15.x to 16.16 (and hence NBAR was added).
Legitimate LogMeIn remote control traffic started getting blocked intermittently under this same NBAR ID 1889 Statistical Peer to Peer. All of our users are using LogMeIn the same way, but I see logs that only about 25% of them were blocked under this rule.
I'm not sure if it's weird or to be expected that these blocks seemed to resolve on their own after like 3 mins to 30 mins. (The users kept trying, and eventually it just worked.) I did find in old NBAR release notes that this rule "Classifies traffic by comparing it to machine-learned clusters", so I'm not sure if the rule adapts in real time, or if the rule just misses some instances sometimes (and so my users were able to connect with LogMeIn on a random instance that NBAR missed).
I guess I'm going to give it a few hours to see how things go, and then probably need to remove the content filter for P2P if there are still issues. Though obviously I'd rather not do that.