My class has a big glass screen at the back where ANYONE can stand and watch what we do. They are also always welcome to come in and watch
I think people fear that if they go down to a wing chun school and say that they do another style of wing chun, they are going to get attacked!!
I have people coming down all the time with backgrounds in BJJ, MT, karate, CMA, etc. They are always welcome to come and watch, as long as they don't disturb the students. Wing chun guys are no different. Everyone is of a different level. Someone might come down who is a better level than me and watch. Someone might come down who is a worse level than me and watch. All I know is that, even the lowest level instructors can come up with great ideas. I am often inspired by lower level instuctors within Kamon, and I will visit their classes and train with their students. Everyone has different experiences and points of view and it is always good to share
There are often seminars hosted by people like James Sinclair or Alan Orr or Alan Ginson around the UK. I try and get to them if I can.