I've never personally worn them, however, I have a lot of experience applying them to my DD for dance competitions. They definitely stay put if applied properly. She doesn't complain about them, so I'm going to guess they are reasonably comfortable.
The trick is to apply them as close to the natural lash line as possible, and allow the glue to air dry for 30 seconds on the lash before applying to your natural lash.
I'd definitely test run them a few times before your big event. They are not easy to apply the first few times. Once you get the hang of it, it's not too bad.