I'm also considering buying flooded properties, but here are my thoughts and concerns.
1) What will future flood insurance costs look like? I've heard that flood maps will not be redrawn quickly, but that it will take years. Therefore, there may be an opportunity to get houses for a good deal and help the thousands of displaced people get a newly rehabbed home to rent.
2) How many people will decide to leave and not come back?
3) I fear buying a flooded house in a neighborhood filled with tons of other empty houses. Let's say I rehab the one I buy, and then half the neighborhood doesn't come back or takes two years to return. What does that mean to the future value of the home? While I think I may be getting a deal, I may just be paying the new market price for the home that will not appreciate for years and years.
4) What does this flood due to the macro-economic picture of South Louisiana. It's hard to get my head around the idea that only about 10% of the people in 60,000 flooded homes had flood insurance. In my mind, this is going to bankrupt a ton of people. Those that don't go bankrupt will have to put all of their hard earned money into their homes and have less disposable income which will crush the economy around here.
5) Real estate investing 101 - invest in the path of growth. Is Baton rouge going to boom with all of the reconstruction or go bust due to the drain on resources of all of these flooded home-owners?
6) Is the an investment opportunity of a lifetime or a risk that will result in future dread?