Jenni,
If you can handle the Mozart and Ravel, then the technical aspect of the Berg sonata will not be a problem for you. I've played the Berg a lot (and Mozart 576) so I know. Technically, there are some awkward things, but nothing harder than what you've already done.
The big, big, big pain for me and for everyone is learning the notes, then memorizing the notes, and also trying to remember all the expression markings. This piece will tax your mind like nothing else.
The good news: it's totally worth it. It's a really rewarding piece.
If you play it and you really get into it, you and I can write more about it. I just finished a 184-page dissertation on it!