I think that having a gate is a small deterrent, but most of the time, that's all it takes to get the bad guy to go somewhere else. Night lights are also very effective at getting bad people to go somewhere else.
In my experience, anytime you have more then one person in charge of or responsible for maintaining something, there will be issues in getting it fixed. I would not want a community gate. If my gate acts up, I'll fix it when I want to, and not when somebody else says I have to, or that I have to pay money to the repair when I might not want to spend that money.
Now that I've had a gate in front of my place for over a year, I really like it. Before, it was a huge pain getting out of my truck to open and close it, so we rarely did that. Now it's always closed, and we have not had a single "visitor" come in that didn't have a valid reason to be there. Before, we had people that claimed to be lost, looking for a dog, or a friend that lived there, or they thought it was a business of some kind. Most of the time, they where believable, but a few times I'm sure that it was a lie and they where checking things out. The most obvious was a very thin couple that had the crack head look to them, who said that they where looking for a lost dog. They didn't know the breed, the color or the dogs name.