From a workload perspective, this year the AHA has taken a great role in reducing the amount of work that the local committee has to undertake. There has been a great push towards "keep it simple." There is a lot of effort that can be put into a conference that really doesn't add much benefit. As this year's conference co-organizer, I appreciate the effort that has been put into managing the scope of the conference.
I think as the conference continues to evolve, they'll be able to shape the scope of the local committee's roles even better to make it even smoother and more managable, despite growth.
Basically, as long as you've got a good community that get get some beer ready, you can pull it off.