Taylor and Taylor produces the insurance for about half of our rental customers (conservative estimate) in the Miami market.
One other issue I'd be aware of: The ability of an insurance agency to know about, and quickly respond to, a Request for a Certificate of Insurance, for both a rental like Doug speaks of, but also for Liability Certificates, when you rent a Location. Several "generalist" agencies that I talked to barely even knew what these were for, and also did not seem set up to be able to quickly respond to those requests. I also found that these generalist agencies charged sizable "per occurrence" fees to produce these Liability Certificates, maybe because they were somewhat foreign to them. As we all know, conditions can change quickly, even the the day before a shoot, due to weather or any other number of factors, and Taylor/Taylor responds very quickly to Liability Certificates; usually within an hour.
Again, this whole topic falls under the heading of the importance of choosing an agency that is not just some generalist neighborhood place, but an agency that deals with photographers' needs on a daily basis. Trust me, the gap is very wide, and it will make itself known very quickly.