There is some characters, which will be hard to replace, but for thugs, torn (zombies) and such I think it will be easy to use lot of proxies.
The rules are really good and the setting is also great.
The only downside so far has been the lack of models released for the first book, which is being done now with the Kickstarter, and also there has been a great need for a set of cards for characters and weapons, which is also being done now.
So hopefully this will be funded and the game will be more widely played!