While I know this is nowhere near as cool as Comfest, I was part of the group that finally decided to start charging at the gate for the Gahanna Jazz and Blues Fest. This had been a free event for years, and attracted crowds of over 20,000 to downtown Gahanna and the surrounding parks.
We heard all these same complaints - people will complain, people will jump the fence, its too hard to fence it off and police it, its against the spirit of the event, its not the way we have always done it, etc. etc.
It came off last year without a hitch, and hardly anyone said a word about it on their way in. They paid their money and went right in, with hardly a problem. This can be done, and it should be. Not wanting to pay $5 for a free day of art, live music and fun is puzzling at best. If its a community festival, why wouldn't you want to support it as a member of the community?
Complaining about a $5 gate fee to get into an event of that size and scope means that you have never tried to organize an event, even on a small scale. Isn't that $5 a small price to pay for a safe and well-run event?