Yeah I was a bit worried about that when I first read it - but I think any errors will be due not to a conflict of information between ASA pubs and Jepps, but due to Jepp users not knowing how to interpret their information properly, or locate it in the manual, like some of the examples given above.
I'd like to know if anybody ever got a question wrong due to the actual data or information in Jepps being wrong or different, as opposed to getting a question wrong cause you didn't familiarise yourself properly with the manual. I'm pretty comfortable with it now - I'm finding myself zipping straight to the correct section when doing practice questions.