Thanks! Despite the fact that we all come from heavy client side rendering backgrounds, you'll find the bulk of our UI is server side rendered :)
Re: compilation errors - It depends on where our script is concatenated in the bundle to an extent. For best results we recommend putting it as the first thing in the bundle.
We went back and forth on this. We orginally just had /current/tracker.js but lots of folks feel weird about running potentially changing scripts on their production sites :) in the end we decided it was probably best to version it and let people upgrade as they see fit. Obviously the backwards compat is a little more work for us, but we felt it was a better choice overall. (You can also bundle our script)
We are working on getting it back up ASAP, in the meantime you can also check out http://trackjs.com which is just static files. (The blog is of course wordpress)
(Edit: After kicking MySql things should be back - also, the rest of our application does not use MySQL :))
1) The performance impact should be functionally negligible. We do instrument a few of the lower level base JS objects but it's all very lightweight. We have not noticed any performance issues thus far. That said, we have some new features coming and we will make anything potentially performance impacting opt-in
2) the buffer of events is currently the latest 10 events from the console, network, and user interaction, for a total of 30. We are looking at modifying this.
3) You can certainly bundle our script, we use the same technique Google Analytics does to capture hits.
4) Nothing, although we currently don't have hard caps and would certainly be in communication with you if you were concerned that was happening!
Re: compilation errors - It depends on where our script is concatenated in the bundle to an extent. For best results we recommend putting it as the first thing in the bundle.