"You can use Presi if you like, but you'd better be ready for having no internet"
I'm pretty sure you can download a Prezi presentation. It's ugly (upwards to 200mb for something simple), but it can be done. Or at least could, I really don't like it, but a friend of mine uses it and he always downloads the presentations.
Tell them about the wonders of tethered phones or whispering quietly Internet dongles.
That's not going to work on the University computers attached to the projectors.
In addition, relying on a mobile phone connection is even more risky.
I once had to help out a struggling interviewee whose Prezi had failed because his laptop wifi wasn't working. Talk about poor choices.