A lot in that post sounds similar to what my dealer was saying but he was basing it on an A4 and not the A5. Actual A5/S5 owners who have already got their cars have confirmed that the information on that link to be incorrect.
The poster in that link is quite wrong. He doesnt understand how the SatNav screen in the A5 is like the A6, not the A4. On the A5 there are no SD slots and the screen doesnt fold down, it is fixed in the MMI screen on the upper part of the dashboard.