There's proposed legislation that would change your sinkhole insurance coverage IF it passes. (Changes won't benefit the homeowner.) You may want to track the legislation and contact your local legislator if you want him/her to oppose this bill. I don't yet live in Florida, so I can't contact anyone.
If this link doesn't work, cut/paste it into your browser.
http://www.sinkteam.com/house-bill-447/