Normally I'm totally with proxies. HOWEVER the other day at a tournament (admittedly a fairly casual one) my opponent was using a Gun smith as Johan. Without the card. Now not only did this mean he took a fair while longer as he checked the book (which due to space couldn't be nearby) he also marked poison and damage wrong.
That coupled with the fact I was using Dr Doug meant that "Johan" kinda tore apart my game plan a fair bit.
I found that frustrating but being a shy dude I didn't really want to argue.