Hey Alex,
I lived in Miami for 7 years and moved to Chicago 4 years ago. I recently organized CodeRetreatMiami.com and a lot of people showed up.
This was unexpected for me. I thought 4 people would registered and 22 people showed up and stayed all day.
My objective with the event was to start paying my dues back to Miami and bring back what I have learned from the tech scene in Chicago.
I contacted a few of the leaders of the local meetups and got good responses from most of them. I also contacted 2 guys that seemed to have been putting a lot into the community and surprisingly both blew me off.
I have been comparing the tech communities of Boston, Austin, Chicago, SF and Miami. People from SF have said that one of the most important key in the startup community is collaboration. By that he meant that you would be able to contact anybody from the tech community no matter how high their position is and most of the times they would be able to give you some time to talk to you.
The same is happening here in Chicago. I could call anybody to ask for advice and they would actually find time for you to meet you. Nobody (so far) is trying to rip off your idea, instead they want to hear your problem and see how they can help.
There are a lot of meetups here and usually a lot of people show up. The meetup with the most attendance is the Lean Startup. On average they get 200 people to a meetup and they come from all over the city and the suburbs. Some people even drive up to an hour and a half to get to those meetups. And not only this but also other tech meetups like Ruby, Android, Drupal. Which means that distance is not important even if we have good transportation system.
The same happens with Austin. You have to drive everywhere just like Miami. Austin has a scene because real state is cheap, a couple of big tech companies are there and there is a college in the middle of downtown.
I would say that even when people say that the problem with Miami is the distances, I would say is not a problem comparing the same to Chicago and Austin.
I would say that the challenges are people communicating with each other, encouraging people to go to events and evangelize an attitude of collaboration.