I'm not exactly sure if events are easier to debug. I use tornado (event-based Python webserver library) extensively at work - when something goes wrong you don't get a nice stack trace, you get some random sampling of callback spaghetti. Also the default state of matters is that everything is serialized in a single thread and everything waits for their predecessor, even when they are totally unrelated, though that probably tells more about the particular framework than event-based programming in general.

I'd rather use a real multithread-based framework, honestly, though I concede that it also opens up different ways of making developers' lives miserable.