Follow up -- as of 02.18.2015 -- we tried it again and for random reasons it started tanking servers again. Nothing special about the servers or the installs:
show processlist from mysql shows that it's running a SELECT * FROM one of its tables (only 5000 rows in it) and it won't finish, then it keeps stacking statements.
The service it provides is great.
But the burden to the database and how it scales with traffic is horrible.
We've now had SEVERAL websites go down because of this plugin.
It just bloats MySQL and we see 1000% CPU usage, 400% memory usage.
The plugin should be using access logs or syslog or something, not assaulting the database.