thank you for this great plugin. I will certainly rate, once I understand what's going on ;) - I activated the plugin yesterday, using twenty twelve and W3TC. There should have been visitors today, I talked to one, but not data was collected. In spite of having read your support threads, I deactivated js mode just to have a try, and now I can see my test visitor (myself in other browser). I expected a warning of kinds, but none so far.
Did I do something weird? Also, I added wp-slimstat.js to the minify exceptions in W3TC. Maybe that made a difference?