"Can anyone tell me about a Yang school that does full contact free sparring, and regularly faces up to other styles?"

Yes--my school, the Great River Taoist Center. My teacher is Scott Rodell, and he's never done any Chen style, only Yang, and he can fight. We practice full-contact sanshou (not the sport sanshou, just as in "free hands"). A 2-year Krav Maga student just came to our sanshou class. He did not fare too well (especially against the older students).

This whole Yang vs. Chen thing is stupid. Just train.